A two-dose combination of the Pfizer vaccine against coronavirus was shown to be efficacious both in clinical trials and real-life situations. Long-term efficacy, although, seems unknown since proof of decreasing protection has emerged in respect of antibodies changes over time and infection immunity. Early results from Israel, where boosters began rolling out progressively in mid-July, show that the Covid vaccination gives additional protection against the coronavirus during a delta epidemic.
According to the researchers, the study, which was disclosed on Tuesday ahead of peer-review and publication, looked at the increased efficacy of a booster injection against infection caused by the delta variation but not a severe illness. The data suggest that a third dosage of the vaccine might be able to offset the fading of vaccine-induced immunity against Coronavirus infection in the near future, according to scientists.
“Leveraging data from Maccabi Healthcare Services, we conducted a preliminary retrospective study aimed at evaluating initial short-term effectiveness of a three-dose versus a two dose regimen against infection due to the Delta variant of SARS-CoV-2, using two complementary approaches; a test-negative design and a matched case-control design. We found that 7-13 days after the booster shot, there is a 48-68% reduction in the odds of testing positive for SARS-CoV-2 infection and that 14-20 day after the booster the marginal effectiveness increases to 70-84%,” reads the study.
An initial review of evidence from Maccabi Healthcare Services revealed that participants who got the additional dosage had a 48 percent to 68 percent reduced risk of becoming infected a week to 13 days later than those who had the conventional two-dose plan. The level of protection grew over time, with a 70 to 84 percent reduction in the chance of testing positive two weeks to 20 days after receiving the third injection.
Israel, a pioneer in Covid-19 vaccinations, announced a record amount of daily cases on Monday, providing new fuel to the country’s vaccine booster campaign.