A latest study has revealed that two doses of Pfizer/BioNTech COVID-19 vaccines are “highly effective” at preventing hospitalisations for at least six months, but protection against the deadly virus nearly halves over the same period. According to the research published in Lancet, the authors said that effectiveness against all Coronavirus infections fell from 88 per cent within a month of having two doses to 47 per cent after six months. However, they also added that effectiveness against hospitalisations remains high at 90 per cent overall, and that too across all variants.
According to the study, the researchers noted that the results of the study are consistent with preliminary reports from the US CDC and Israel’s health ministry that suggested protection against the virus fades within six months. They said that the findings underscore the vital importance of improving COVID-19 vaccination rates globally. They further added that their study confirms that vaccines are a “critical tool” for controlling the pandemic.
In the research, the authors said that the vaccines “remain highly effective in preventing severe disease and hospitalisation, including from the Delta and other variants of concern.”
The authors of the study analysed the health records of three million people between December 2020 and August 2021. During the period, the researchers reveal that 5.4 per cent of people were infected with SARS-COV-2. The average time since being fully vaccinated against Coronavirus was between three and four months.
The study found that Pfizer vaccine effectiveness against Delta variant infections at one month after two doses was 93 per cent and fell to 53 per cent after four months. The researchers also found that effectiveness against other variants at one month after receiving two doses was 97 per cent and declined to 67 per cent after four months. However, the researchers did not observe a difference in waning between-CoV-2 variant types.
Dr Luis Jodar, senior vice-president and chief medical officer of Pfizer vaccines, said, “Our variant-specific analysis clearly shows that the BNT162b2 vaccine is effective against all current variants of concern, including Delta. Covid-19 infections in people who have received two vaccine doses are most likely due to waning and not caused by Delta or other variants escaping vaccine protection.”
Moreover, the researchers noted that considerations for booster shots should take the global COVID-19 vaccine supply into account as people in several nations across the globe have not yet received a primary vaccination series. However, the authors of the study could not determine causal relationships between vaccination and COVID-19 outcomes as vaccination status among the study population was not randomised. They also did have data on adherence to mask guidelines, social interactions, occupation and disease rates, which could impact the likelihood of contracting and being tested for the deadly virus.