An interesting paper reviewed this issue. 

They found that vaccinated individuals who had become infected with SARS-CoV-2 had a lower rate of secondary household transmission compared to unvaccinated index individuals.  

Over 550,000 residential households were sampled between January to March 2021 in England.  

They found that the overall SARS-CoV-2 secondary attack rate was 5.7% in households where the index case had received at least one dose of the Oxford AstraZeneca vaccine. 

6.3% in households where the index case had received the Pfizer vaccine more than 21 days before testing positive.  

By contrast, the overall secondary attack rate in households with unvaccinated index cases was about 10%.  

In a case controlled analysis, contacts of index cases vaccinated with the Oxford AstraZeneca vaccine had a 38% lower odds of SARS-CoV-2 infection compared to matched contacts of unvaccinated index cases.  

Similarly, contacts of index cases vaccinated with the Pfizer vaccine had 49% lower odds of infection.  

However, it was noted that only 7% of the vaccinated index cases had received two vaccine doses by the time of their infection and thus the risk of secondary transmission infection may be even lower in those who have had two doses.  

Their findings provided emerging evidence that receipt of at least one dose of either vaccine reduced transmission of SARS-CoV-2 to from a diagnosed case to other persons in the household setting. 

The London General Practice as a leading London doctors’ clinic commends the Government on its vaccination programme and encourages all those who are eligible to be vaccinated.

Dr Paul Ettlinger

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