Pfizer vaccine- Is it really effective?

Thota Kanishka Rao, Amity University Kolkata

Coronavirus became a household name, as the pandemic swept people off their feet, locking them in their houses, rendering them sick, leading to death on severe occasions. After months into the pandemic, in December 2020, the government of Israel approved the BNT162b2 COVID-19 vaccination and proclaimed a mass immunization campaign prioritizing health-care workers (HCWs). Just as Israel, governments of other nations, including India, also did the same, although this coincided with the third-wave of COVID-19.

Clinical experimental data of the BNT162b2 COVID-19 vaccination showed vaccine efficacy in preventing COVID-19 of 52•4% before dose two, and 90.5% on days 2–7 after dose two. Though, very recent observation of BNT162b2 vaccine data estimated vaccine efficacy of 89–91% during days 15–28 following the first dose.

But, as more and more people get vaccinated and others await their turns, the most common question that arises is if they could delay the second dose of vaccination to get more people vaccinated and how immunized are they after the first dose.

A single dose of covid vaccine is deemed to be very effective, but a second dose is very much important, not only for an individual’s health but also for the nation’s health, as governments throughout their world figure out how to deliver more vaccine to everyone who requires it.

Recently, results showed that the efficiency of a single dose of Pfizer vaccine is up to 85%. December 19, 2020, saw the vaccination campaign in Israel and researchers observed the rate of reduction in SARS-CoV-2 infection and COVID-19 disease. By January 24, 2021, nearly 7000+ HCWs received the first dose of vaccine and approximately more than 6500+ HCWs received their second dose of vaccine. On the whole, there were 170 cases of infection between December 19, 2020, and January 24, 2021. Out of these individuals, 89 people, or 52%, were unvaccinated, while 78 people, or 46%, tested positive after the first dose and 3-2%, tested positive after receiving the second dose.

This result was consistent with the findings of the phase 3 experimentation data, which stated that the 52% protection from the first dose included infections that occurred within the first 10 days.

Using the above data, the Pfizer vaccine was deemed to be 89% effective for 15-20 days following the initial dose of vaccination and before dose 2 on day 21. The range was around 52 – 97%. For 15-28 days or up to the first week, after receiving the second dose of the vaccine, the protection from the first dose was estimated at 91% and the range was around 74 – 97%. A second dose was not expected to confer immunity within that timeframe.

In India, medical workers urged the people to get both the doses of the Pfizer or Moderna vaccine, to be reassured that even a single dose of either of those vaccines, would provide high levels of protection that our body has time to build immunity, in within a week. The scheduled second dose of these vaccines makes them even more effective, but as the vaccines are limited, the first dose has been prioritized for a lot of people.

Also read: https://bioxone.in/

Source: Amit, S., Regev-Yochay, G., Afek, A., Kreiss, Y., & Leshem, E. (2021). Early rate reductions of SARS-CoV-2 infection and COVID-19 in BNT162b2 vaccine recipients. Lancet (London, England), 397(10277), 875–877. https://doi.org/10.1016/S0140-6736(21)00448-7

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