Vaccination works - but a small number “are still at increased risk”

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Men are more at risk of experiencing severe complications from the COVID-19 virus than women even after vaccination, although the risk is low, according to a Scottish study involving the University of Strathclyde.

The research found that 0.07% of partially vaccinated people and 0.006% of fully vaccinated people suffered a serious case of the virus. It is the first national study of COVID-19 outcomes in Scotland after vaccination.

The research, published in medical journal The Lancet Respiratory Medicine, found that fewer than one in 2,000 partially vaccinated people and fewer than one in 10,000 fully vaccinated people in Scotland suffered a serious case – hospitalisation or death – of COVID-19 between December 2020 and April 2021, when there were high background levels of infection.

The study found that, although the risk for men was around 25% higher than for women, those aged in their 80s were five times at greater risk than those aged 18-64. Those who had multiple underlying health conditions, had been admitted to hospital in the previous four weeks, had a high-risk occupation, lived in a care home or lived in a deprived area were also at greater risk, even after having received both doses of a vaccine.

A severe case of COVID-19 is defined as one involving hospitalisation or death within 28 days of a positive test or with COVID-19 recorded as the reason for admission to hospital.

The UK-wide consortium of researchers also included the Universities of St Andrews, Aberdeen, Glasgow and Edinburgh and Public Health Scotland.

Professor Chris Robertson, Professor of Public Health Epidemiology in Strathclyde's Department of Mathematics and Statistics, was a partner in the study. He said: “This study shows that after just one dose of vaccine, the rate of covid hospitalisation or death is very low at a time when the alpha variant was circulating in Scotland.

“However, the individuals who are most at risk of having a severe infection while vaccinated are the same as those at most risk from a severe outcome from COVID-19 infection – elderly individuals with multiple co-morbid conditions.

“It is important to ensure that such individuals minimise their exposure risks and get the second and booster doses of the vaccine.”

The COVID-19 vaccination programme in Scotland began on 8 December 2020 with the Pfizer-BioNTech vaccine. This was then followed by the Oxford-AstraZeneca vaccine from 4 January 2021 after approval from the Medicines and Healthcare products Regulatory Agency (MHRA).

Of the 2.57 million adults who had received the first dose of a vaccine, only 883 were admitted to hospital with COVID-19 and 541 died within the period studied. Nearly 700,000 people received their second vaccine in this period – 27% of those included in the study, with just 39 of those (0.006%) suffering a serious case of COVID-19.

The study also found that having had COVID-19 before receiving a vaccine reduced the risk of serious COVID-19 even further.

The authors report that, taking age, sex and level of social deprivation into account, people with a history of asthma, chronic kidney disease, heart failure, type 2 diabetes, dementia and coronary heart disease were at increased risk of serious COVID-19 after a vaccination.

The team will now continue to analyse the outcomes for those who have suffered a serious case of COVID-19 following second and, in eligible individuals, booster vaccine doses.

They also plan to extend this work from the focus on Pfizer-BioNTech and Oxford-AstraZeneca in this analysis to other vaccines such as Moderna, which are now beginning to be administered at scale. In addition, they plan to investigate outcomes in children and young people who are now eligible for COVID-19 vaccinations.

The study used data from the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19 (EAVE II), which was funded by UK Research and Innovation (Medical Research Council); Research and Innovation Industrial Strategy Challenge Fund; the Scottish Government; the National Institute for Health Research (NIHR); and Health Data Research UK.