Human Vaccines & Immunotherapeutics

ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/khvi20

Vaccines and routine immunization strategies

during the COVID-19 pandemic

Ener Cagri Dinleyici, Ray Borrow, Marco Aurélio Palazzi Safadi, Pierre van
Damme & Flor M. Munoz

To cite this article: Ener Cagri Dinleyici, Ray Borrow, Marco Aurélio Palazzi Safadi, Pierre
van Damme & Flor M. Munoz (2021) Vaccines and routine immunization strategies during
the COVID-19 pandemic, Human Vaccines & Immunotherapeutics, 17:2, 400-407, DOI:
10.1080/21645515.2020.1804776

To link to this article: https://doi.org/10.1080/21645515.2020.1804776

Published online: 26 Aug 2020.

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HUMAN VACCINES & IMMUNOTHERAPEUTICS
2021, VOL. 17, NO. 2, 400–407
https://doi.org/10.1080/21645515.2020.1804776

REVIEW

Vaccines and routine immunization strategies during the COVID-19 pandemic

a
Ener Cagri Dinleyici , Ray Borrowb, Marco Aurélio Palazzi Safadi c
, Pierre van Dammed, and Flor M. Munoze
a
Department of Pediatrics, Eskisehir Osmangazi University Faculty of Medicine, Eskisehir, Turkey; bVaccine Evaluation Unit, Public Health England,
Manchester, UK; cDepartment of Pediatrics, Santa Casa De São Paulo, School of Pediatrics, São Paulo, Brazil; dCentre for the Evaluation of Vaccination,
Vaccine & Infectious Disease Institute, University of Antwerp, Antwerp, Belgium; eDepartments of Pediatrics and Molecular Virology and Microbiology,
Baylor College of Medicine, Houston, TX, USA

ABSTRACT ARTICLE HISTORY

Severe acute respiratory syndrome coronavirus 2 related disease (COVID-19) is now responsible for one of Received 6 May 2020
the most challenging and concerning pandemics. By August 2020, there were almost 20 million confirmed Revised 12 July 2020
cases worldwide and well over half-million deaths. Since there is still no effective treatment or vaccine, Accepted 30 July 2020
non-pharmaceutical interventions have been implemented in an attempt to contain the spread of the KEYWORDS
virus. During times of quarantine, immunization practices in all age groups, especially routine childhood Coronavirus; COVID-19;
vaccines, have also been interrupted, delayed, re-organized, or completely suspended. Numerous high- immunization; pandemic;
income as well as low- and middle-income countries are now experiencing a rapid decline in childhood vaccine
immunization coverage rates. We will, inevitably, see serious consequences related to suboptimal control
of vaccine-preventable diseases (VPDs) in children concurrent with or following the pandemic. Routine
pediatric immunizations of individual children at clinics, mass vaccination campaigns, and surveillance for
VPDs must continue as much as possible during pandemic.

In December 2019, a novel coronavirus, SARS-CoV-2, was first that were controlled or even eliminated.8 With control strate­
reported in Wuhan, China, and rapidly spread throughout the gies to prevent the spread of COVID-19 affecting childhood
world, resulting in a pandemic within 3 months.1 COVID-19 is and mass immunization campaigns worldwide, millions of
the acute respiratory disease caused by this new virus. By children are now at risk of other deadly vaccine preventable
August 2020, there were almost 20 million confirmed cases diseases.9 By contrast, in countries that are easing restrictions,
worldwide and well over half-million deaths.2 Although the there is a potential risk of outbreaks of diseases like measles,
disease occurs in all age groups, mortality is mostly seen in pertussis, and polio, among others.
older people and individuals with co-morbidities.3–5 Since The first epidemiological data from Wuhan showed that
there is still no effective treatment or vaccine, measures imple­ children make up a small portion of COVID-19 patients, and
mented for the control of COVID-19 include non- the need for intensive care among pediatric patients is very
pharmaceutical interventions (including serious curfews in low.10 Soon thereafter, data from Italy, Spain, and the United
some countries), canceling mass gathering activities, and man­ States (US), where the disease has spread widely, also showed
dating social distancing, school closures, and travel restrictions. that children constitute only a small number of hospitalized
While the impact of COVID-19 varies among countries world­ patients.11–13 Infected children, as a group, seem to have
wide, through these measures, societies are trying to reduce the a milder clinical course, lower hospitalization, and intensive
use of healthcare facilities by decreasing the spread of the virus care requirements, and in rare cases mortality.14 Recently, case
and minimizing virus-related morbidity and mortality rates.6,7 reports and case series from the United Kingdom, Italy, France,
This has resulted in a disruption of commerce, travel, and Switzerland, and the United States have raised concerns about
health care During times of quarantine, routine health-care a severe systemic disease manifestation related to SARS-CoV-2
services and elective surgical procedures have been stopped infection in children. The US Centers for Disease Control and
in many health-care settings, and health-care professionals Prevention (CDC) has referred to this condition as
have been organized in such a way as to support or prioritize “Multisystem Inflammatory Syndrome in Children (MIS-C)
the care of increasing numbers of COVID-19 patients. At the associated with COVID-19.”15 Social distancing measures,
same time, immunization practices in all age groups, especially such as closing schools and imposing lockdowns, have already
routine childhood vaccines, have also been interrupted, had some beneficial effects on common childhood infections
delayed, re-organized, or completely suspended.8 When that are transmitted via droplets, respiratory secretions, or the
immunization programs are stopped or interrupted for any fecal–oral route.16 This has clearly been shown for influenza.17–
19
reason, we may observe an increasing number of vaccine- However, children remain at risk for these and other vaccine
preventable infections and related deaths, in addition to preventable diseases, particularly upon the gradual removal of
a fraction of the population that became susceptible to diseases isolation and quarantine conditions. Routine immunization

CONTACT Ener Cagri Dinleyici timboothtr@yahoo.com Department of Pediatrics, Eskisehir Osmangazi University Faculty of Medicine, Eskisehir TR-26040,
Turkey
© 2020 Taylor & Francis Group, LLC
 HUMAN VACCINES & IMMUNOTHERAPEUTICS 401

remains a key intervention against vaccine-preventable dis­ postponed because of social distancing issues.22 The Global
eases in children. Routine immunizations for pregnant Polio Eradication Initiative recommended suspending polio
women, adults, and elderly persons, and patients with chronic vaccination campaigns until the second half of 2020.21 As
conditions, and higher risk, are also essential. a result of the coronavirus pandemic, 46 poliovirus immuniza­
tion campaigns in 38 countries, mostly in Africa have been
suspended. During this time, a mutated vaccine-derived strain
Routine immunizations during the COVID-19
of poliovirus has been reported in >30 countries.20 Following
pandemic
the suspension of these immunization activities, there has been
COVID 19 is disrupting life-saving immunization services a new polio outbreak in Niger.24 In Pakistan and Afghanistan,
around the world, putting millions of children – in industria­ wild poliovirus Type 1 have been reported, and cases of Type 2
lized as well as in low- and middle-income countries – at risk of poliovirus, mutated from the oral vaccine, have appeared in
vaccine-preventable diseases. Because of the risk of infection Chad, Ethiopia, Ghana, and Pakistan.25
and the need to maintain physical distance during the early During the pandemic, 37 countries (home to 117 million
stages of the COVID-19 pandemic, many countries have tem­ unvaccinated children) suspended scheduled measles cam­
porarily and reasonably suspended preventive mass vaccina­ paigns, and more will be postponed.22 Before the pandemic,
tion campaigns against diseases such as measles, polio, and despite the availability of an effective vaccine, the highly
diphtheria, pertussis, polio, tetanus, meningitis.20 Causes of contagious measles virus continued to spread around the globe.
the delayed/interrupted immunizations are due to parents’ In 2018, cases surged to an estimated 10 million worldwide,
fears, restrictions of movement/lockdown policies, changing with 140,000 deaths, a 58% increase since 2016.22 Measles
priorities for COVID-19 among health-care personnel, and outbreaks have been reported in diverse settings, including
logistics delivery issues (i.e., vaccine transport delays). The Madagascar and Ukraine.26–28 In 2019, measles outbreaks
World Health Organization (WHO), UNICEF, and GAVI, infected more than 6,500 children in the Democratic
the Vaccine Alliance have reported that routine immunization Republic of the Congo where one-dose measles vaccine cover­
programs have been substantially disrupted in at least 68 age was 57%.22,29 In 2019, in many countries faced vaccination
countries, affecting around 80 million children.20 A further coverage rates below the minimum needed for herd immunity;
24 million people are at risk of losing out on vaccines including this posed a serious risk to children who were not vaccinated
measles, polio, rotavirus, meningitis, rubella, and human papil­ and indirectly threatened immunocompromised children and
lomavirus in GAVI-supported low-income countries.20 others who could not be vaccinated for other medical contra­
Vaccines are of critical importance in these areas, which also indications. Eighteen countries reported measles outbreak due
have limited access to health services and treatments. Due to to suspended measles campaigns. By 2020, 178 million people
the risk of inadvertently contributing to the spread COVID-19, are at risk of skipping measles vaccines, according to the
global health organizations have not been able to continue to Measles and Rubella Initiative, even as measles flares across
support mass vaccination campaigns in some countries.8,21,22 the globe, including in Afghanistan, Brazil, Cambodia, the
Of the 129 countries in which data were available, more than Central African Republic, Iraq, Kazakhstan, Nepal, Nigeria,
half reported moderate to severe disruptions, or total suspen­ and Uzbekistan.23
sion of vaccination services during March – April 2020. There In many countries, vaccine hesitancy and refusal have
was a full cessation of routine immunizations from April 1–15, become an important problem in recent years.30 Several serious
2020 in Vietnam. In India, routine immunizations were dis­ measles outbreaks have been seen in low- and middle-income
rupted due to health-care workers being re-organized in countries (LMIC), due to other problems such as broken and
response to the pandemic. In Pakistan, polio catch-up immu­ underfunded health systems, which make it nearly impossible
nization campaigns were postponed until June 1st, 2020.8 to deliver vaccines to those who need them.24,26 During the
A number of countries postponed immunization campaigns COVID-19 pandemic, families’ reluctance and fear to attend
in the first 5 months of the pandemic, including: measles or health-care services to administer childhood measles or
measles-containing vaccines in 27 countries, inactivated polio measles–containing vaccines may lead to an increase in the
vaccine in 7 countries, bivalent, or monovalent oral poliovirus number of unvaccinated children and further increased rates of
vaccine in 39 countries, meningococcal conjugated A vaccine measles disease and its complications.
in 2 countries, yellow fever vaccine in 4 countries, typhoid The suspension of measles vaccination campaigns, which
vaccine in 2 countries, oral cholera vaccine in 5 countries, have occurred in 24 countries where measles remains an urgent
and Td (tetanus–diphtheria) vaccine in 7 countries.20 While health condition, could also have long-lasting implications.22
several mass immunization campaigns have been stopped to Due to school closures, serious immunization disruptions may
prevent the virus spreading, the results have been alarming. occur in countries where routine immunizations have been
Diphtheria has recently resurged in countries like Venezuela, delivered in school settings. According to UNESCO data
Pakistan, Nepal, Bangladesh, and Yemen where conflict and/or from April 15, 2020, 91% of the world’s school-age children
population displacement have seriously affected public health have stopped their education due to the pandemic.31 Measles is
systems.23 Cholera is now present in Bangladesh, Cameroon, a disease that can cause serious morbidity and has a case-
Mozambique, South Sudan, and Yemen.23 fatality rate of 0.2%, it is more highly contagious (basic repro­
The WHO’s Strategic Advisory Group of Experts on duction rate; R0 as 12–16) than COVID-19.32 If children are
Immunization issued a broader call, recommending that all left unvaccinated, case numbers could quickly surge following
preventive mass vaccination campaigns for other diseases be a drop in the optimal population immunity and the suspension
402 E. C. DINLEYICI ET AL.

of these vaccination programs. Measles weaken the immune April 2019.40 During the first 3 weeks of the lockdown, the
system for months or years, causing immune amnesia that number of measles, mumps, and rubella vaccines delivered in
leaves children susceptible to other infections.33 England fell by 20%, and smaller drops were reported in infant
Similarly, polio is an important concern, and suspending vaccines in Scotland. In Indonesia, a recent study showed that
polio immunizations is a particularly relevant issue where the 84% of immunization services have been disrupted by the
virus is likely to spread (e.g., Afghanistan and Pakistan) due to COVID-19 pandemic, and 19.7% drop in measles–rubella vac­
active circulation. The risk of polio spreading to other coun­ cinations in April 2020.41 In Ethiopia, when the pandemic
tries is real, and could negatively affect global polio eradication struck, the country suspended measles campaign, though the
efforts.21,34 country continues to report many new cases23 Immunization
COVID-19 has virtually affected all countries of the world, coverage has dropped among adults too, due to similar con­
regardless of their economic power, but represent a particular cerns and fears about attending routine medical care.42 In the
threat for LMIC’s, because of their limited political and eco­ United States, compared with May 2019, immunization rates
nomic leverage for battling the disease alongside other major dropped by 30% in adults, with the largest percentage drop
problems, including efforts to control vaccine-preventable dis­ among 19- to 49-year-olds.43
eases. One preprint study has recently shown that, for each A decline in immunizations could endanger the 90–95%
death caused by COVID-19 acquired from an immunization vaccination coverage that is necessary for herd immunity
visit, there could be more than 100 children’s deaths in Africa, against diseases such as measles, mumps, and whooping
prevented by continuing routine immunizations. This suggests cough. Primary care vaccine intake is highest when parents
that the health benefits of deaths prevented by sustaining feel safe, when parents receive timely notice that vaccines are
routine childhood immunization in Africa far outweigh the due, and when health care workers have processes to ensure
excess risk of COVID-19 deaths associated with vaccination effective call-back and recall programs.37 Despite the chal­
clinic visits.35 For this reason, ensuring the continuation of lenges brought on by the pandemic, several countries are
timely of measles and polio vaccine administration is vitally making special efforts to continue immunizations.
important for all countries, particularly since it is not known
how long the pandemic will last. With existing inexpensive and
Potential effects of existing vaccines on COVID-19
effective vaccines, we still have a chance to control and elim­
pandemic
inate these diseases. There is also collateral damage related to
COVID-19. In the Democratic Republic of Congo, the measles Pneumococcal and influenza vaccines are also being discussed
epidemic since January 2020 alone has led to more than 60,000 in the context of the COVID-19 pandemic. COVID-19 infec­
cases and 800 deaths. Ebola, tuberculosis, and cholera are also tions are severe among patients of all groups, but especially
striking the country.23 those over age 65.3–5 An increase of COVID-19 frequency and
After 5 months of pandemic, there is new information about mortality has also been seen in patients with chronic lung and
the potential determinants of the decline of routine immuniza­ cardiovascular diseases and diabetes, all of which are risk
tions. Parental fears about potentially exposing their children factors for pneumococcal infections.44 Previous experience
to COVID-19 during routine follow-up visits may have led to has shown that pneumococcal infection risk is also increased
the declines observed.36 Some states in US have reported drops in patients with a previous influenza infection.45 In studies
compared to the same period 1 year earlier, for measles and conducted to date among COVID-19 patients, there is no
other vaccine preventable diseases. There, according to the data indicating an increased risk of pneumococcal infections;
Vaccines for Children Program between 2019 (January 7– therefore, there has been no suggestion of applying pneumo­
April 21, 2019) and 2020 (January 6–April 19, 2020), there coccal vaccines (either conjugated or polysaccharide vaccines)
was a corresponding 21.5% decline in measles-containing vac­ to provide protection against COVID-19-associated pneumo­
cines administrations as of March 16, 2020.36 In Michigan, nia, including in the at-risk group of patients over 65 years of
when compared with the period from May 2016 to May 2019, age.46 A majority of countries include conjugated pneumococ­
approximately 50% of infants aged 5 months were up-to-date cal vaccines in their national childhood immunization pro­
on all recommended vaccines in May 2020, while about two- grams and recommend conjugated and/or polysaccharide
thirds of children (66–68%) were up to date during the past 4 vaccines for high-risk groups and elderly people. Routine
years.37 In US, publicly funded vaccines including hepatitis, immunizations that include pneumococcal vaccines for chil­
meningitis, polio, and rotavirus, were also sharply down com­ dren and high-risk adults should continue according to pre­
pared to 2019. In New York City, vaccinations have been down viously developed schedules, to reduce the need for hospital
63% overall, and by 91% for children older than age two, in admissions for vaccine-preventable diseases.
California, have been down 40%.38 In Ohio, pediatric vaccina­ The effect of COVID-19 on seasonal influenza epidemics is
tion rates are down about 45%; where normally there were unknown at this time. However, the confluence of COVID-19
about 1,000 measles given shots in a month, in April 2020, and seasonal influenza during the fall and winter of 2020–2021
there were just 32.39 The Virginia Department of Health has might result in considerable morbidity and mortality, and
reported that between March 15 and April 23, 2020, vaccina­ stress to the health system. Health systems and all of society
tions dropped 45.7% compared to the same time period in alike must prepare for the likelihood of co-epidemics of
2019, with an 83% drop among children age 5 and younger. COVID-19 and influenza.47 In the Northern hemisphere,
The human papilloma virus vaccine was among those with the COVID-19 began to circulate toward the end of the seasonal
largest drop-off, with65% lower coverage in 2020 than in influenza period, and social distancing and isolation/
 HUMAN VACCINES & IMMUNOTHERAPEUTICS 403

quarantine measures have resulted in a dramatic end to the vaccination (such as Italy, the Netherlands, and the US) have
spread of influenza.48 There are limited data related to co- been more severely affected, compared to countries with long-
infection rates of influenza with COVID-19.8,49,50 As influenza standing universal BCG policies (such as Portugal).56,58 The
vaccination rates remain suboptimal for most populations, attributed potential nonspecific effects of the BCG vaccine in
including those at greater risk for severe COVID-19, the co- preventing COVID-19 remain a hypothesis, given multiple
circulation of viruses may result in increased mortality risk confounding factors. The BCG vaccine has been used in some
during the upcoming influenza season. Influenza tends to countries during the newborn or early infancy periods, and the
peak in Europe and the US between December and April of BCG vaccine offers consistent protection only against severe
each year, and during the months of June through August in form of tuberculosis in children, but observational studies have
the Southern Hemisphere, therefore, the experience of coun­ shown that, during childhood, vaccinated children have better
tries in the Southern Hemisphere during their winter will be overall survival rates, including when facing respiratory
informative to Northern Hemisphere countries.47 The viruses.59,60 In 2018, the BCG vaccine was shown to stimulate
Southern Hemisphere influenza season is beginning, as of initial immune defenses well enough that it at least partly
this writing, but there is only low, or even no activity reported blocked another virus given experimentally 1 month later.59
so far, probably due to lockdowns implemented in the region.51 The WHO, however, has recommended not using the TB
The majority of illnesses that are being reported is COVID-19. vaccine to fight COVID-19 until further studies are being
High influenza vaccine coverage would reduce influenza- conducted.61 As of mid-June 2020, there were ongoing clinical
related mortality while also helping to preserve the capacity trials to evaluate the effect of this TB vaccine among health care
and function of the health system during circulation of both workers in the Netherlands, Australia, the United States, Egypt,
influenza and COVID-19 viruses. The goal should be to attain and France.62–65
high influenza vaccine coverage, including near-universal cov­
erage among health-care personnel and other high-risk groups
Routine immunizations in children and adults with
for COVID-19.47,52 Improving rates of seasonal influenza vac­
suspected or confirmed COVID-19 infections
cination is critical for the management of the influenza and
COVID-19 co-circulation anticipated in the next several There is currently no evidence that vaccination would increase
months and until a COVID-19 vaccine is available. the risk of a child becoming infected with COVID-19, or affect
The increased susceptibility to severe disease in the elderly the course of the disease in a child who has been inadvertently
and those with co-morbidities for COVID19, argues for vaccinated during the asymptomatic phase or incubation
a possible alteration in anti-viral host defense mechanisms period.66 In general, routine infant and school-age immuniza­
additional to immunosenescence. Previous studies showed tion should not be postponed. Most children with COVID-19
that live vaccines (i.e., BCG, oral polio vaccine, measles) induce are asymptomatic or have mild symptoms, therefore testing
heterologous protection against infections, likely by inducing before vaccination is not recommended. There is no clear gui­
interferon and with a long-term boosting of innate immune dance on the administration of routine vaccines in children with
immunity mechanisms.53 Data from clinical studies of the oral COVID-19, or those who have tested positive for the virus but
polio vaccine show that this approach reduced infant mortality who have no symptoms or known contact. Individuals with
by roughly 32%, reduced the burden of bacterial diarrheal signs of acute respiratory infection, including mild symptoms
disease, and has been associated with fewer episodes of acute such as sore throat or runny nose, may postpone regular immu­
otitis media diagnosed by medical doctors.54 Measles and nization until they have recovered during the COVID-19 pan­
smallpox vaccines have also been associated with pronounced demic. Anyone with suspected, possibly, or confirmed COVID-
nonspecific protective effects against infectious diseases. 19 and those who are close to a case should not attend scheduled
Recent reports indicate that COVID-19 may result in sup­ appointments for immunization during their isolation time.
pressed innate immune responses. Some have proposed Patients with COVID-19 infections present with different symp­
(hypothetically) that oral poliovirus vaccine, in particular, toms and signs, including fever, cough, runny nose, and gastro­
could provide temporary protection against COVID-19. Both intestinal issues. The presence of fever may cause confusion
poliovirus and coronavirus are positive-strand RNA viruses; concerning vaccine side effects or the progression of the illness;
thus, specific innate immunity mechanisms are likely to induce therefore, vaccines can be postponed until illness resolution, in
and affect these viruses. Advantages of oral poliovirus vaccines cases of acute febrile illness.66,67 The CDC recommends defer­
are low cost, ease of administration, availability and well- ring vaccinations of anyone infected with SARS-CoV-2, regard­
known safety profile.54 Further randomized controlled trials less of symptoms, until they meet the criteria to discontinue
with oral poliovirus vaccine may provide some information for isolation. Although mild illness is not a contraindication to
potential beneficial effects of COVID-19 infections.55 vaccination, deferring makes it possible to avoid exposing
Another controversial issue concerning vaccines is the sug­ health-care personnel or other patients to COVID-19. Among
gested protective effect of the tuberculosis Bacillus Calmette– confirmed cases of infection, it would be reasonable to postpone
Guerin (BCG) vaccine on COVID-19 infections.56,57 Such an vaccinations until resolution of the illness, particularly in hospi­
effect has not been demonstrated in clinical studies, and obser­ talized and moderate and severe cases. It is also prudent to delay
vational data have not clearly shown that, in countries where the administration of any live vaccines among COVID-19
the BCG vaccine is routinely administered, the frequency and patients who have been treated with immunoglobulin or plasma,
mortality of COVID-19 is less common.56 It has been sug­ according to routine live vaccine use protocols. Mild symptoms
gested that countries without universal policies of BCG such as fever and/or cough are not necessarily a contraindication
404 E. C. DINLEYICI ET AL.

for vaccination.66–68 In line with normal procedures, health-care rooms visited by bundling medical examinations and vaccina­
providers should make recommendations based on a risk–ben­ tion services during such visits. When visiting a healthcare
efit assessment severity of symptoms and risk and severity of institution, wearing a mask is beneficial for everyone. In the
vaccine preventable diseases. If the practitioner decides against US, masks are recommended for those age 2 and older, while in
vaccination on that day, the normal vaccination schedule for the Europe they are suggested for those over the age of 12.70 Hand
child should be resumed as soon as possible after he or she hygiene facilities (soap and/or sanitizers) should also be pro­
recovers. If post-exposure prophylaxis with vaccine or immu­ vided. In pediatric settings, all toys should be removed from
noglobulins is required (e.g., measles, hepatitis A, hepatitis B, immunization rooms, and social distancing opportunities
rabies, meningococcus, varicella), it should be given without should be considered by requiring appointments (Figure 1).
delay. There is no known interference between the COVID-19 There are no additional personal protective equipment
test or between COVID-19 and the tuberculin test.67 requirements during routine immunizations; a surgical mask
Vaccination of newborns is considered an essential service, is sufficient. Patients should avoid crowded waiting rooms by
particularly in low- and middle-income countries, where BCG scheduling well-checks and immunizations in advance. Only
and hepatitis B vaccine are administered before maternity one parent (wearing a mask) should attend the immunization
discharge. In cases of mothers with a laboratory-confirmed clinic with a child. Clinics should provide ventilated areas and
diagnosis of COVID-19, asymptomatic newborns could be ensure the feasibility of social distancing for caretakers and
vaccinated according to local recommendations with BCG children awaiting immunization. For vaccines not included in
and hepatitis B vaccine. If the newborn presents COVID-19 national immunization programs (i.e., optional ones), the par­
symptoms, the BCG vaccine should be postponed and the ent should collect the vaccine from a pharmacy and deliver it in
hepatitis B vaccine might be administered within the first accordance with cold chain transfer protocols. After the pan­
24 hours of life.69 demic period, if some patients have missed age-appropriate
immunizations, there is no need to re-start an immunization
series or to add extra doses. Longer than recommended inter­
Immunization measures during the COVID-19
vals between doses typically do not affect immunogenicity and
pandemic
The WHO recommends that all routine vaccinations be admi­
nistered as scheduled, even during the COVID-19 pandemic.
Routine immunization sessions should continue, using special
measures and precautions, to the extent possible and as per­
mitted within the local COVID-19 response context. This
includes routine immunization for infants, children, adoles­
cents, pregnant women, high-risk groups, and adult health-
care providers.68 Any interrupted immunization services
should be resumed and catch-up vaccinations offered as
quickly as possible.66
Following the existing guidelines on COVID-19 infection
prevention measures during immunization sessions, health-
care providers should prioritize primary series vaccinations,
especially for measles–rubella- or poliomyelitis-containing
vaccines and other combination vaccines. Mass vaccination
campaigns should be avoided until the COVID-19 situation
resolves. Newborns should be vaccinated as per the national
immunization schedule in maternity hospitals, and vulnerable
population groups should still receive pneumococcal and sea­
sonal influenza vaccines.66 New vaccines should be delayed
from introduction to national immunization schedules. It
should be communicated clearly to the community and health-
care professionals alike the rationale for the inclusion of immu­
nizations among the priority health services provided during
the COVID-19 pandemic. The risks from VPDs and the ben­
efits of vaccination should also be reiterated.66,67
For routine pediatric immunization visits, prior to the
appointment, children, parents, and caregivers should be
advised not to attend if they have any COVID-19 symptoms.
Control measures should include all forms of protection for
vaccine providers, those being vaccinated, and those accom­
panying them, to reduce the risk of transmission. It is also
Figure 1. Control measures for immumization visit during the COVID-19 Pandemic:
advised that parents consider combining vaccination visits Including appointment, wearing a mask, hand hygiene, social distancing and
with well-baby visits and that they reduce the number of immunization room.
 HUMAN VACCINES & IMMUNOTHERAPEUTICS 405

potential protection. Immunization service providers should much as possible during the pandemic. Parents are some­
also start enumerating the cohorts of children who have missed times fearful about bringing their children to a clinic, but
their vaccine doses and develop an action plan for custom close relationships between the parents and the vaccinators
catch-up immunization services. All available communication and implementation of safeguards to reduce the risk of
technology should be used to communicate about immuniza­ exposure and infection would resolve this problem.
tion services, including setting appointments and reporting The ongoing COVID-19 pandemic is a reminder of the
adverse events following an immunization. importance of vaccination as a critical public health strategy
Perhaps in a later phase of the pandemic, alternate locations for disease prevention and control. Public health officials have
could be considered for school or seasonal influenza vaccina­ agreed that the most important global protection strategy,
tions, while maintaining social distancing and enhanced infec­ and the best method for controlling the SARS-CoV-2 pan­
tion control strategies. Units should be created where COVID- demic, is a vaccine. An effective vaccine will require
19 patients are not cared for, so patients may receive routine a minimum of 1–2 years to be developed, using the most
vaccinations without risk of exposure. By designating specific optimistic forecast.75–78 It is unknown how long the pan­
appointment times, it is possible to ensure that only well demic will last, or what the course of the virus spread will
patients are in the clinic during those times. Appointments be after the first wave. While some of the strategies used to
also minimize the number of people present in the clinic at slow the spread of the virus in the community include using
once. telemedicine, instead of face-to-face encounters, for routine
Vaccine hesitancy/refusal has been one of the most impor­ medical visits, every effort should be made to continue rou­
tant health problems in recent years, and during the COVID- tine immunizations for children and persons at risk for vac­
19 period, the most radical groups have continued to share cine-preventable diseases. The potential for vaccine shortages
false and non-evidence-based opinions with the community.30 related to closing borders and limited transport during the
Many of these theories posed during the pandemic have the pandemic are also causes for concern. The disruption of
risk of increasing future vaccine refusals. One of the most routine health-care services and attendance to routine medi­
important observations during the period has been that the cal home visits due to social distancing and isolation condi­
speed of transmission of false information about the disease is tions can continue. Although we know that there will be
much faster and more dangerous than the speed of the spread many demands on health systems and frontline health-care
of the virus.71 workers during and beyond the threat of COVID-19, conti­
Reduced access to critical health-care facilities and medi­ nuing preventive health services, especially children’s vacci­
cations is known to establish circumstances in which patients nations, are of great importance for the months and years to
use substandard drugs and/or dosages. This could lead to come. Whenever possible, providers are encouraged to prior­
increased morbidity and mortality caused by human immu­ itize newborn care and vaccination of infants and children
nodeficiency virus infection, tuberculosis, and malaria, as well when a healthcare practice can only provide limited well-child
as leading to the rise and spread of drug-resistant diseases.72 visits. Otherwise, we will inevitably see serious consequences
These populations need protection not only from the pan­ related to suboptimal control of vaccine-preventable diseases
demic, but also from the consequences of non- in children concurrent with or following the SARS-CoV-2
pharmaceutical interventions. In addition to low- and mid­ pandemic.
dle-income countries, other vulnerable populations for the
pandemic and mitigation strategies consequences are refu­
gees and migrants. The pandemic has had an enormous effect Disclosure of Potential Conflicts of Interest
on mobility, border and migration management, and on No potential conflicts of interest were disclosed.
global migrant populations’ health, social, and economic
situation. There now needs to be an immediate concerted
effort to link these communities with national and global ORCID
responses to COVID-19.73 During the pandemic, immuniza­ Ener Cagri Dinleyici http://orcid.org/0000-0002-0339-0134
tion program for refugees and immigrants should not be Marco Aurélio Palazzi Safadi http://orcid.org/0000-0002-4401-9446
neglected.
COVID-19 pandemic represents one of the most challen­
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