More than a week back, the Centers for Disease Control and Prevention (CDC) released data that indicated that immunity levels of people vaccinated with the Pfizer-BioNTech shot dropped significantly after four months of
full inoculation.

The CDC study found that after around four months, the immunity of the fully vaccinated dropped to 77 percent from over 90 percent during the period from 15 days to 120 days.

Israel also saw similar results for the Pfizer vaccine. The data from that country showed that the citizens who had been among the first to receive the vaccine were catching the Covid virus. (https://edition.cnn.com/2021/10/06/health/pfizer-vaccine-waning-immunity/index.html)

Should people worry about these results?

"I think that we expect that immunity will slowly wane, over time, but it's not a reason for people to panic," said Dr. Ann Falsey, a specialist in viral respiratory diseases at the University of Rochester School of Medicine to CNN. The positive thing according to Falsey is that the "breakthrough infections" as they called among those getting Covid despite being fully vaccinated are are colds and flu-like illnesses. These may not result in death as it is the case with -- not the scary illnesses that we were facing before," she added. (https://edition.cnn.com/2021/10/09/health/pfizer-covid-vaccine-waning-questions-wellness/index.html)

Scientists say that cellular immunity is what will protect people from the disease. They say that 'Memory B cells' which can produce antibodies to a virus, can stay longer and same is the case with T cells, which attack already-infected cells. These play an essential role. (https://www.nature.com/articles/d41586-021-02532-4)


But the fear of the Delta variant of the coronavirus and the the vaccine waning in immunity has prompted many to rush for booster shots. For instance, an analysis of CDC data shows that the number of people receiving booster shots is outpacing those getting their first or second doses of the initial vaccination across the U.S. This has led to an increase in Covid vaccinations in October.

Read more:

What is going on with booster shots?
https://www.healthline.com/health-news/what-is-going-on-with-covid-19-boosters

COVID vaccine immunity is waning — how much does that matter?:
https://www.nature.com/articles/d41586-021-02532-4