Paris: Two jabs of the Pfizer vaccine is highly effective against severe Covid-19, including Delta variant, and protection stays for at least six months, an analysis on US patients found. The study published, on Monday, in the journal Lancet measures one vaccine's effectiveness over time in the real-world setting, while previous data on clinical trials has shown jabs protect against hospitalisation.
Pfizer and the healthcare provider Kaiser Permanente analysed records from 3.4 million residents of southern California, from which a third were fully vaccinated between December 2020 and August 2021. After an average of three to four months, fully vaccinated people were found to be 73 per cent protected against infection and 90 per cent against hospitalisation. Though protection against disease from Delta variant fell by 40 per cent after five months, protection against hospitalisation caused from all variants remained very high during the study.
The results and study notes stood consistent with initial data from the US and Israeli health authorities. The report's authors concluded that reduced infection defence is primarily due to waning vaccine effectiveness rather than Delta variant bypassing vaccine protection.
They said their findings stress the importance of monitoring vaccine effectiveness over time and the need for booster doses to restore the initial high amounts of protection observed at the start of the vaccination drive.
In August, the US authorised an extra dose of vaccine for those who are immunocompromised, while France gave the same for the elderly. Israel went a step further by jabbing the third on children of 12 and older.
However, a September report by the World Health Organisation (WHO) stated that current vaccines are effective enough against severe Covid. A third dose is not necessary for the general population. Last month, the organisation had called for a moratorium on booster jabs until the end of the year, addressing the enormous inequity in dose distribution between rich and poor nations.