Evidence has shown that COVID-19 vaccines reduce severity of disease as well as viral load. The latest study to corroborate this is the REACT-1 study.

Findings of the latest findings of the REACT-1 study, conducted between 24^th June and 12^th July, show that persons who are fully vaccinated are three times less likely to be infected with SARS-CoV-2. The latest 13^th round of the REACT-1 study involved 98,233 volunteers, who took a swab (nasal and throat) test at home.

This study found 527 positive samples on RT PCR, which shows an overall prevalence of 0.63% or 1 in 160 people indicating a 4-fold rise in prevalence when compared to the last report, which covered the period between 20^th May and 7^th June and the prevalence was 0.15%. Whole genomic sequencing of 254 positive samples detected Delta variant in all (100%) samples, whereas in the preceding round, the percentage of detection of delta variant was 78.3%, with the remaining being alpha variant.

The highest prevalence was found in young people aged 13-24 at 1.56%, or 1 in 65 infected, while the lowest was in people aged ≥75 years at 0.17%. Women had a lower risk of testing positive than men (0.55% vs 0.71 %). The R number was estimated at 1.19, corresponding to a doubling time of 25 days suggesting that the spread of the virus had slowed down by the end of the study period.

The unvaccinated individuals had three times higher chances of testing positive for COVID-19 than the fully vaccinated people; 1.21% vs 0.40%, respectively. They were also less likely to test positive than unvaccinated persons after coming in contact with a person with COVID-19; 3.84% vs 7.23%, respectively).

Compared to the unvaccinated people, the fully vaccinated reduced their risk of infection including asymptomatic infection by 50%-60%. They were also less likely to transmit the virus to others.

REACT (REal-time Assessment of Community Transmission) is a series of studies, which use home testing to assess the prevalence of COVID-19 across England. It has been commissioned by the Department of Health and Social Care (DHSC) and is being carried out by Imperial College London in partnership with Ipsos MORI and Imperial College Healthcare NHS Trust. The REACT 1 study uses antigen (swab) testing to monitor the level of current infections, including asymptomatic individuals and also identify the at-risk persons. The REACT-1 round 13 interim results have been published as a preprint.

Studies have established the protective benefits of the currently available COVID-19 vaccines. But no vaccine offers 100% efficacy; hence, there is always a risk of getting infected. Post-vaccine breakthrough infections have been reported. But, the benefits of vaccination still outweigh the risks and it is important that all eligible persons should take the vaccine. Vaccination must be complemented by protective measures such as face masks, hand washing, physical distancing, avoiding crowded public places. Continued surveillance is essential for timely detection of trends in the prevalence of cases and implementation of measures to curb the spread of infection.

(Source: Press release, dated 4.8.21, https://www.gov.uk/government/news/react-study-shows-fully-vaccinated-are-three-times-less-likely-to-be-infected)