Current Status Of Global Covid Vaccines And Immunization

Introduction

The pandemic of Covid-19 began from Wuhan Province of China in the later parts of December 2019. The WHO declared the Covid -19 epidemic a “Public Health Emergency of International Concern” on 30^th January 2020. As at 16:37 GMT, 3^rd January 2022, there have been 290,994,646 confirmed cases of Covid -19, including 5,462,688 deaths globally, as reported to WHO, affecting 222 countries and territories. Myanmar had reported 531,155 total cases and 19,277 deaths by 1^stJanuary 2022.(1) The Chinese scientists had shared the genetic sequence of SAR-COV2 virus since 12^th January, 2020, within two weeks after the announcement of clusters of cases of unusual pneumonia in Wuhan.(2) Since the availability of genetic sequence, many scientists all over the world are trying to start developing diagnostic tests as well as steps for development of vaccines.

Vaccines as a game -changing tool

As many previously deadly infectious diseases were effectively controlled by the development of safe and effective vaccines, many scientists have expected and tried to develop vaccines as early as possible. Equitable access to safe and effective vaccines is critical to ending the Covid -19 pandemic, so it is an encouraging achievement to see so many vaccines proving and going into development. It was reported on 2^nd December 2021 that out of 7,849,695,228 UN estimated world population 2,493.102,902 (less than one third) were vaccinated with at least one dose of Covid vaccines and 1,412,522,559 (less than one fifth) were fully vaccinated.(3) As there are many problems of equitable distribution of vaccines and ongoing emergence of genetic variants of concern, although safe and effective vaccines are a game-changing tool for the foreseeable future we must continue wearing masks, cleaning our hands, ensuring good ventilation indoors, physically distancing and avoiding crowds. (4)

Accelerated Vaccines Development

Traditionally, development of a vaccine to use in human takes about 10 years. Because of the urgency of needing a safe and effective Covid vaccines we had witnessed the accelerated timeline of Covid vaccines in 2021. CanSino launched the world’s first Covid -19 vaccine trial, in Wuhan on 16^th March 2020.(5) But the first vaccines to be approved by a stringent National Regulatory Body was the PfizerBioNTech vaccine. It was approved for Emergency Use Listing (EUL) by UK drug regulatory authorities on 2^nd December 2020. (6)

Vaccines in development

There were 194 candidate vaccines in pre-clinical development and 137 candidate vaccines in clinical development up to 28th of December, 2020. Among the vaccine candidates in clinical phases Protein subunit vaccines were most common type constituting 47 (35%) followed by RNA vaccines 23 (17%), viral vector (non-replicating), 20 (15%) and inactivated vaccines 18 (13%) respectively.

It is noted that the majority of vaccine candidates in clinical phases i.e. 83 (61%) need two doses and intramuscular injection 105 (77%) is the most common route. Four (3%) of candidate vaccines can be given by oral route. (7)

Registration status of different covid vaccines

There is wide variation in different registration status among various candidate vaccines. Up to 21^st December 2021, ten vaccines already obtained WHO Emergency Use Authorization (EUA) status. Thirty were approved for use in at least one national authority.

Figure (1) Overview of Covid 19 vaccines market dashboard (8)

Comparison of WHO -EUL Covid Vaccines

Table (1) Comparison of ten WHO – EUL vaccines (9) (10) (11)

Vaccines and variants

The delta (B.1.617.2) variant is nearly twice as contagious as earlier variants and might cause more severe illness. The greatest risk of transmission is among unvaccinated people. People who are fully vaccinated can get vaccine breakthrough infections and spread the virus to others. However, it appears that vaccinated people spread Covid -19 for a shorter period than do unvaccinated people. While research suggests that Covid -19 vaccines are slightly less effective against the delta variant, the Pfizer-BioNTech, Moderna and Janssen/Johnson & Johnson COVID-19 vaccines still appear to provide protection against severe Covid -19. Covaxin was reported to be 65 % (33-83) effective against delta variant.

The omicron (B.1.1.529) variant might spread more easily than other variants, including delta. But it is not yet clear if omicron causes more severe disease. It is expected that people who are fully vaccinated can likely get breakthrough infections and spread the virus to others. However, the Covid -19 vaccines are expected to be effective at preventing severe illness. Pfizer reported that booster dose exhibit improve protection from omicron. This variant also might reduce the effectiveness of some monoclonal antibody treatments. (12)

Covid Vaccination in Pregnant and Lactating mothers

In the interim, WHO recommends vaccination in pregnant women when the benefits of vaccination to the pregnant woman outweighs the potential risks. E.g. pregnant women at high risk of exposure to Covid -19 – pregnant women with comorbidities that place them in a high risk group for severe Covid -19. Pregnant women should be provided with information about the: risks of Covid -19 in pregnancy, likely benefits of vaccination in the local epidemiologic context and current limitations of the safety data in pregnant women. It is not necessary to conduct pregnancy testing prior to vaccination and there is no need to delay or terminate pregnancy because of vaccination.

Covid -19 vaccines cannot Covid -19 infection in anyone, including the mother or the baby, and vaccines are effective at preventing Covid -19 in people who are breastfeeding. Recent reports have shown that breastfeeding mothers who have received mRNA Covid -19 vaccines have antibodies in their breastmilk, which could help protect their babies. More data are needed to determine what level of protection these antibodies may provide to the baby. (13)

Booster dose of Covid Vaccines

Vaccine booster dose policy decisions should be based on evidence of individual and public health benefit and obligations to secure global equity in vaccine access as a means to minimize health impacts and transmission, and thereby reduce the risk of variants and prolongation of the pandemic. Vaccine supply is growing, but many countries are far from reaching the 40% coverage target by the end of 2021 by WHO, whilst other countries have vaccinated well beyond this threshold, already reaching children and implementing extensive booster vaccination programs. At present, globally about 20% of Covid -19 vaccine doses daily, are used for booster or additional dose vaccination. At least 126 countries worldwide have already issued recommendations on booster or additional vaccination and more than 120 have started programmatic implementation. No low-income country has yet introduced a booster vaccination programme.

Up to date, the evidence indicates a minimal to modest reduction of vaccine protection against severe disease over the 6 months after the primary series, which is more marked in above 50 year olds. Both homologous and heterologous booster regimens are immunologically effective.

The most commonly prioritized target populations for booster doses are older adults, health workers and immunocompromised individuals (in immunocompromised individuals the booster dose is considered as an additional primary series vaccination dose by WHO. WHO suggested the first priority of a vaccination programme is to reduce mortality and severe disease and to protect health systems. (14)

Covid vaccines for Children

Children can also get infection with Covid-19 infection and they can also transmit to others, but they have a very low risk for severe diseases. Some of the Covid vaccines have already been authorised for use in children. WHO is currently not recommending the general vaccination of children and adolescents as the burden of severe disease in these age groups is low and high coverage has not yet been achieved in all countries among those groups who are at highest risk of severe disease’.

WHO recommended as a matter of global equity, as long as many parts of the world are facing extreme vaccine shortages, countries that have achieved high vaccine coverage in their high-risk populations should prioritize global sharing of Covid -19 vaccines through the COVAX facility before proceeding to vaccination of children and adolescents who are at low risk for severe disease.

It is of utmost importance for children to continue to receive the recommended childhood vaccines for other infectious diseases. (15)

Conclusions

Development of an effective, safe and widely available Covid-19 vaccines is considered as a game-changing tool of Covid-19 pandemic. Energetic, collaborative efforts of scientists all over the world lead to the development of various effective vaccines and already relieved the health, social and economic impact in many different regions of the world. The world is facing the challenges of inequitable distribution of vaccines to most vulnerable population in the low income countries and regions and as well as the emergence of Variants of Concerned (VOCs) which can change the effectiveness of vaccines and disease severity. Equitable distribution of vaccines is the most important and urgent challenge to solve intelligently by world leaders as “No one is safe until everyone is safe”.

References

1. World Health Organization. Covid Live- Coronavirus Statistics – World Meter. [Online]. Available from: https://r.search.yahoo.com/_ylt=Awr9Gi8LcNRh_PkAZ1xXNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641341067/RO=10/RU=https%3a%2f%2fwww.worldometers.info%2fcoronavirus%2f/RK=2/RS=wYzVDelr5Xg8cYzk6Yl2WSR0S0M-[Accessed 3rdJanuary 2022]
2. World Health Organization Timeline:WHO’s COVID-19 response? [Online]. Available from: https://www.who.int/emergencies/diseases/novel-coronavirus-2019/interactive-timeline [Accessed 26 November 2020].
3. World Health Organization. Dedicated Covid 19 vaccine dashboard) (27 December 2021)[Online]. Available from: https://app.powerbi.com/view?r=eyJrIjoiMWNjNzZkNjctZTNiNy00YmMzLTkxZjQtNmJiZDM2MTYxNzEwIiwidCI6ImY2MTBjMGI3LWJkMjQtNGIzOS04MTBiLTNkYzI4MGFmYjU5MCIsImMiOjh9[Accessed 3rd January 2022]
4. World Health Organization. Covid 19 vaccines – WHO. [Online]. Available from: https://r.search.yahoo.com/_ylt=AwrE19g7LdNh5wUASRhXNyoA;_ylu=Y29sbwNiZjEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641258427/RO=10/RU=https%3a%2f%2fwww.who.int%2femergencies%2fdiseases%2fnovel-coronavirus-2019%2fcovid-19-vaccines/RK=2/RS=8KnZMY1qUbl6IobaeOqH6hYhN0I-[Accessed 3rd January 2022]
5. Chemical &Engineering News. CanSino publishes first COVID-19 vaccine data to muted response. [Online]. Available from: https://cen.acs.org/pharmaceuticals/vaccines/coronavirus-help-mRNA-DNA-vaccines/98/i14?utm_source=mostread&utm_medium=mostread&utm_campaign=CEN [Assessed 4th January 2022]
6. Wikipedia- Pfizer–BioNTech COVID-19 vaccine.[Online]. Available from: https://r.search.yahoo.com/_ylt=AwrTLZIDlNRhXGMAuY1XNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641350276/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fPfizer%25E2%2580%2593BioNTech_COVID-19_vaccine/RK=2/RS=T9E9GPUQWBwJkK4F3.ITA9dUwnY-[Assessed 3rd January 2022]
7. WHO -Covid-19 Landscape of Novel coronavirus candidate vaccines worldwide ,28 December https://r.search.yahoo.com/_ylt=A2KLfSgNOtNh4kwAxcZXNyoA;_ylu=Y29sbwNiZjEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641261709/RO=10/RU=https%3a%2f%2fwww.who.int%2fpublications%2fm%2fitem%2fdraft-landscape-of-covid-19-candidate-vaccines/ RK=2/RS=ECrD2m69zibIYTtaSrbMzGytUiA-[Assessed 3rd Jan 2022]
8. COVID-19 Vaccine Market Dashboard. 21st December 2021, https://r.search.yahoo.com/_ylt=AwrE19U7P9NhaKQA_wxXNyoA;_ylu=Y29sbwNiZjEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641263035/RO=10/RU=https%3a%2f%2fwww.unicef.org%2fsupply%2fcovid-19-vaccine-market-dashboard/RK=2/RS=X81KBDqToW _gFqgWf2mNkBmS5pU-
9. World Health Organization. COVID-19 vaccines WHO EUL issued,Dec23 2021.[Online]. Available from: https://r.search.yahoo.com/_ylt=Awr9CI6bldRhHUcAsAtXNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641350684/RO=10/RU=https%3a%2f%2fextranet.who.int%2fpqweb%2fvaccines%2fvaccinescovid-19-vaccine-eul-issued/RK=2/RS=aXyci YFfJxb1ki6SNqnAN12IWAo- [Assessed 4th January 2022]
10. Wikipedia-Covaxin.[Online]. Available from: https://r.search.yahoo.com/_ylt=Awr9Imp3ltRhM6sA8StXNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641350904/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fCovaxin/RK=2/RS=XlNSr9Xg4DhspmFjmioTszCwmwo-[Assessed 4th January 2022]
11. Wikipedia –Novavax-Covid 19 vaccine. [Online] Available from: https://r.search.yahoo.com/_ylt=Awr9BHwZl9RhpAMAmiBXNyoA;_ylu=Y29sbwNncTEEcG9zAzMEdnRpZAMEc2VjA3Ny/RV=2/RE=1641351066/RO=10/RU=https%3a%2f%2fen.wikipedia.org%2fwiki%2fNovavax_COVID-19_vaccine/RK=2/RS= KpBKvUIv2rN656IW qFtGtJQyNfM- [Assessed January 2022]
12. Mayo Clinic-Do COVID-19 vaccines protect against the variants? 30 Dec 2021[Online]. Available from: https://r.search.yahoo.com/_ylt=Awr9Du34l9RhGPEAZQhXNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641351288/RO=10/RU=https%3a%2f%2fwww.mayoclinic.org%2fcoronavirus-covid-19%2fcovid-variant vaccine/RK=2/RS=nw LjEzZe6EyoHhVdXU1FWu1gJD4- [Assessed 4th January 2022]
13. WHO- Update on WHO Interim recommendations on COVID-19 vaccination of pregnant and lactating women. June 10 2021. [Online]. Available from: https://www.who.int/news-room/feature-stories/detail/the-sinovac-covid-19-vaccine-what-you-need-to-know#:~:text= need%20to%20know,The%20Sinovac%2DCoronaVac%20COVID%2D19%20vaccine%3A%20What%20you%20need%20to%20know,-2%20September%202021 [Assessed 4th January 2022]
14. WHO: interim statement on booster doses for COVID-19 vaccination, Update 22 December 2021. [Online]. Available from: https://r.search.yahoo.com/_ylt=AwrT4afaKNRh_e8AmEFXNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641322842/RO=10/RU=https%3a%2f%2fwww.who.int%2fnews%2fitem%2f22-12-2021-interim-statement-on-booster-doses-for-covid-19-vaccination—update-22-december-2021/RK=2/RS=wNeoLpFFLqZ69Irlgkx95h9Iefs
    [Assessed 4th January 2022]
15. WHO- Interim statement on COVID-19 vaccination for children and adolescents.24 November 2021.[Online]. Available from: https://r.search.yahoo.com/_ylt=Awr9CJ.xndRhbJAAO4hXNyoA;_ylu=Y29sbwNncTEEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1641352753/RO=10/RU=https%3a%2f%2fwww.who.int%2fnews%2fitem%2f24-11-2021-interim-statement-on-covid-19-vaccination-for-children-andadolescents/RK=2/RS=Cp.VnmcdoE5X2vuhxty8SpG0PJ8- [Assessed 4th January 2022]

Author Information

Saw Win
MBBS, DCH, MMedSc(Paed.), MRCPCH, FRCP.
Former Professor/Head, Department Paediatrics, University of Medicine
Member, Immunization Technical Advisory Group, WHO-SEAR
Vice Chairman, National Immunization, Technical Advisory Group (NITAG)