Pfizer vaccine efficacy wanes three months after second jab, study finds

Pfizer vaccine efficacy wanes three months after second jab, study finds

SCIENTISTS have found that the effectiveness of the Pfizer/BioNTech vaccine wanes three months after the second dose.

This means the risk of Covid-19 infection increases following a person’s second dose, and so the new findings supports the case for booster vaccines to prevent people with reduced immunity getting infected with the virus, the research team argued in the British Medical Journal (BMJ).

Though many European countries are seeing a spike in infection rates, the same uptick has not occurred in the UK.

Astra Zeneca CEO Pascal Soriot hinted on the BBC Today programme that the disparity could be due to the longevity of the immunity offered by the Astra Zeneca jab, as opposed to Pfizer.

One explanation for this could be that at the time when vaccine orders were being placed, there was a greater focus on “efficacy” rates.

This tests the extent to which fast-acting antibodies, or “frontline fighters”, can attack the virus.

While this the most desirable function when the pandemic was still in an acute stage, and much of the world had little-to-no immunity and were still in lockdown, it is arguably less of an advantage in the current, more advanced stage of the pandemic.

“Everybody focussed on antibodies but these antibodies decline over time. What remains is the T-cell response,” Soriot said.

He continued: “This vaccine has been shown to stimulate a T-cell response to a higher degree in older people. We haven’t seen a lot of hospitalisations in the UK. A lot of infections to be sure, but what matters is how ill you are”.

While the Pfizer study is observational, and therefore not the most reliable, experts have said it appears clear that immunity wanes after the first three months of a second jab.

They said: "Large scale Covid-19 vaccination campaigns can achieve control over the spread of the virus, but even in countries with high vaccination rates, breakthrough infections can occur.

"The risk of infection in adults who received two vaccine injections increased with time elapsed since vaccination compared with the reference (individuals vaccinated in the last 90 days)."