COVID-19 vaccines created a historical landmark as the quickest developed vaccine in the vaccine catalogue. Monumental technological advancement and enormous support and collaboration among scientific groups around the globe made it possible. Since the beginning of the pandemic, science has uncovered a lot about SARS-CoV-2 and achieved extraordinary milestones on COVID-19 vaccine development, but still, there is substantial uncertainty as the pandemic continues to evolve.
The pandemic will end at some point and the world will then go back to normal again. But when that would happen, no one knows yet. Some scientists fear coronavirus to be a permanent phenomenon, like polio, measles, or the flu virus. So, it may turn into seasonal flu, but possibly with a significantly lower rate of mortality than now.
While the vaccination is real, what is unreal today are the expectations of attaining “herd immunity”. Either natural infection or mass vaccination or both will help achieve a “herd immunity threshold”. Many scientists had thought that the beginning of mass vaccination will help achieve herd immunity (estimated at a threshold of 60-70% of the people) to permit society to return to normal. But as the pandemic continues to spread in 2021 with a greater number including emerging new variants, the thinking has begun to shift. Moreover, unequal distribution and increasing debates on “vaccine nationalism” raise a big concern against fighting the corona pandemic.
Nearly 2.15 billion doses of coronavirus vaccines have been administered in around 230 countries so far. After a year of breakneck research and brainstorming developmental work into nearly 240 vaccine candidates, nearly a dozen COVID-19 vaccines are effectively used globally. Some of them are mentioned here:
- Pfizer-BioNTech vaccine
The Pfizer-BioNTech vaccine BNT162b2 is developed by the US pharma giant Pfizer in collaboration with the German biotechnology company BioNTech and sold under the brand name Comirnaty. It is an mRNA vaccine that carries the necessary spike protein information and is in use for teenagers (12 years and above) to adults. The pfizer-BioNTech vaccine needs two shots three weeks apart and the full protection occurs two weeks after the second shot. This vaccine is approved in 85 countries, while clinical trials are in place in 24 other countries.
- Moderna vaccine
The Moderna Therapeutics COVID-19 vaccine mRNA-1273 is developed by the American biotech company Moderna, the United States National Institute of Allergy and Infectious Diseases (NIAID), and the Biomedical Advanced Research and Development Authority (BARDA). This mRNA vaccine is in use for people age 18 years and older. There are two shots given within a 4 weeks interval and the full protection occurs two weeks after the second shot. Moderna vaccine is approved in 47 countries with an ongoing clinical trial phase in 21 countries.
- Oxford-AstraZenica vaccine
The Oxford-AstraZenica vaccine AZD1222 is sold under the brand names Covishield and Vaxzevria. It is an adenovirus vector-based (ChAdOx1) DNA vaccine and developed by Oxford University and the British-Swedish multinational pharmaceutical company AstraZenica. This is a double-dose vaccine. The shots are recommended within a time interval of 12-16 weeks, while it may vary slightly from country to country. It is approved for people over 16 years of age. Vaxzevria is approved in 99 countries, while Covishiled is approved in 40 countries.
- Janssen vaccine
The Janssen vaccine Ad26.COV2.S is an adenovirus vector-based DNA vaccine, similar to Oxford-AstraZenica, developed by Janssen Vaccines, Netherland and its Belgium parent company Janssen Pharmaceuticals, a subsidiary of American company Johnson & Johnson. To date, this is the only vaccine that needs a single shot, and the full protection occurs within two weeks of the shot. People over the age of 18 can take this vaccine. Janssen vaccine is approved in 42 countries and the clinical trials are ongoing in 17 other countries.
- Sputnik V vaccine
The Sputnik V is another one adenovirus vector-based DNA vaccine in the COVID-19 vaccine catalogue and developed by the Gamaleya Research Institute of Epidemiology and Microbiology in Russia. The Russian Ministry of Health registered this vaccine as Gam-COVID-Vac. The ‘V’ in its name is the letter, not the Roman numeral. Sputnik V is a double-dose vaccine with two different preparations. The dose recommendation was initially three weeks and now extended to three months. It is approved in 68 countries and the clinical trials progress in 6 countries.
As of now, the BBV152 is the only inactivated viral vaccine that gained more attention globally and sold under the brand name Covaxin. It is developed by the Indian multinational biotechnology company Bharat Biotech in collaboration with the Indian Council of Medical Research. Covaxin needs two shots at an interval of 4-6 weeks. Presently this is approved in 9 countries.
With the rapid increase in the number of SARS-CoV-2 cases, there are reports of emerging mutants or variants of coronavirus. The coronavirus variants were first observed in the United Kingdom, South Africa, Brazil, and India. These variants are of much concern as they resulted in around a 30% increase in infectivity and spread compared to the original counterpart. This means that 30% more people, so a total of 90% of people, should be vaccinated to achieve herd immunity, which is not going to be an easy task. On the other hand, even though the data suggest full vaccination can protect from corona infection, it is still unclear to what extent vaccination reduces transmissibility.
A mutation is a natural process for viruses as they keep changing, and most of the mutations are inconsequential, while only a few become lethal. There are thousands of different mutants of SARS-CoV-2 circulating across the world. Only a few of them are of special concern as they are suspected to hinder vaccine activity. Those variants are termed as “variants of concern” and are strictly under the scanner. Most important of them are the Indian variant B.1.617.2, the UK or Kent variant B.1.1.7, the South African variant B.1.351, and the Brazil variant P.1. All these variants carry mutations in their spike protein, which is the prime target for vaccine development.
The vaccine producers claimed and published data supporting vaccines are effective against some of the variants, at least to some extent; but more data needed to support these claims, especially for the latest emerging variants. Scientists strongly believe that existing vaccines can be redesigned or modified to better tackle emerging variants. Furthermore, the need for a booster dose will also depend on how variants continue to develop.