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Vaccination effective against severe COVID-19 but some groups still at risk

The risk of serious COVID-19 is very low among partially and fully vaccinated people, but vaccinated men, older people and people with multiple underlying health conditions are still at risk, according to a nationwide study in Scotland.

The EAVE II study found that fewer than one in 2,000 partially vaccinated people and fewer than one in 10,000 fully vaccinated people in Scotland were hospitalised or died after contracting COVID-19 between December 2020 and April 2021, when there were high background levels of infection. This translated to a 0.07% risk of severe COVID-19 in partially vaccinated people and 0.006% in fully vaccinated people.

Of the 2.57 million adults who received the first dose of a vaccine - either Pfizer-BioNTech or Oxford-AstraZeneca - between December 2020 and April 2021, 883 were admitted to hospital with COVID-19 and 541 died. Nearly 700,000 people received their second vaccine in this period – 27% of those included in the study - with 39 of those experiencing a serious case of COVID-19.

The study reported in The Lancet Respiratory Medicine that having had COVID-19 before receiving a vaccine further reduced the risk of serious subsequent infection.

The research, funded by NIHR and UK Research and Innovation, also found that some groups were still at high risk of complications from COVID-19 despite being vaccinated. The risk for men was around 25% higher than for women, and people in their 80s were at five times higher risk than those aged 18-64.

People who had been admitted to hospital in the previous four weeks or had multiple underlying health conditions were also at risk, with asthma, chronic kidney disease, heart failure, type 2 diabetes, dementia and coronary heart disease all increasing vulnerability. Profession and location also had a role, with people in high-risk occupations, and those living in care homes or deprived areas, more vulnerable even if vaccinated.

Professor Aziz Sheikh, Director of the University of Edinburgh’s Usher Institute and EAVE II study lead, said: “No vaccine is 100% effective. These data, from our national analysis of over 2.5 million COVID-19 vaccines, show that the risk of developing severe COVID-19 leading to hospital admission or death after at least one vaccination was – thankfully – very low. Based on this analysis, we would encourage anyone who has not yet been vaccinated to take up the offer as soon as possible.

“By identifying the characteristics of those most at risk of serious COVID-19 outcomes after vaccination, clinicians will, we hope, be better informed about which patients may require particularly close monitoring if they develop COVID-19.”