Study Boosts Importance of COVID-19 Booster Shots


The efficacy of the Pfizer/BioNTech vaccine wanes 6 months after the second dose to about 50%, but not because of the Delta variant, according to a study in The Lancet.

COVID-19 vaccines are not the sole answer, according to the latest scientific data, although they are the biggest part of the answer. The question being: When are we going to finally emerge from this pandemic? Of course, other mitigation efforts help: hand hygiene, social distancing, and masking. However, a large retrospective cohort study unveiled yesterday suggests that booster shots will go a long way in getting our pre-COVID-19 lives back.

That study, published yesterday in The Lancet, found that the efficacy of the Pfizer/BioNTech vaccine falls somewhat precipitously 6 months after the second dose to about 50%. On a positive note, that drop-off was not caused by the highly infectious Delta variant that has had the US and the other countries on the ropes for months and, for the most part, the vaccine keeps people out of the hospital.

“Our results provide support for high effectiveness of BNT162b2 against hospital admissions up until around 6 months after being fully vaccinated, even in the face of widespread dissemination of the Delta variant,” the study states. “Reduction in vaccine effectiveness against SARS-CoV-2 infections over time is probably primarily due to waning immunity with time rather than the Delta variant escaping vaccine protection.”

The study was funded by Pfizer.

Kevin Kavanagh, MD, a member of Infection Control Today® ‘s (ICT®’s) Editorial Advisory Board says that the study “confirms the need to administer boosters to all with waning immunity. Stopping the spread of disease is a high priority not only to prevent severe acute illness and long COVID but also to prevent viral mutations. Vaccines appear to be a vital strategy in lowering the R0 of SARS-CoV-2 below 1.0 and should be used in combination with surgical or N95 masks, social distancing, testing, contact tracing and improvements in building ventilation.”

Data were collected from 3.4 million people receiving care in the Kaiser Permanente Southern California (KPSC) health care system from December 14, 2020, to August 8, 2021. Individuals fully vaccinated with the Pfizer/BioNTech vaccine overall had 73% protection against infection and 90% protection against hospitalization.

“Related to other findings from Israel, the USA, and other countries, our findings underscore the importance of monitoring vaccine effectiveness over time and suggest that booster doses are likely to be needed to restore the initial high amounts of protection observed early in the vaccination program,” the study states.

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