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Sir Patrick Vallance, the UK’s chief scientific adviser, has announced that 40% of people admitted to hospital with COVID in the UK have received two doses of a coronavirus vaccine. At first glance, this sounds very serious alarm bells, but it shouldn’t. Vaccines still work very well.
Several factors at play explain why such a high proportion of cases are fully vaccinated.
COVID vaccines are extremely effective, but none are 100% effective. This is not surprising in itself – flu shots are also not 100% effective. Yet in the United States alone, influenza vaccines are estimated to prevent millions of cases of illness, tens of thousands of hospitalizations and thousands of deaths each year. COVID vaccines are doing the same in the UK right now – just compare the curves of the winter wave with those of this summer.
As cases increase, so do hospitalizations and deaths, but not to a level comparable to winter. In the second half of December 2020 – a period when UK case rates were similar to what they are now – around 3,800 people were admitted to hospital with COVID each day. The average is now around 700. So while it’s still higher than we’d like, it’s a lot lower than the last time we had so many infections.
COVID is also increasing among those vaccinated as the number of people in the UK who have received both doses continues to rise. At the time of writing, 88% of UK adults have received a first dose and 69% a second. As more and more of the population are vaccinated, the relative proportion of people with COVID who have had both vaccines will increase.
If you imagine a hypothetical scenario where 100% of the population is doubly vaccinated, then 100% of people with COVID, and hospitalized with COVID, will also have had both vaccines. As with deaths, that doesn’t mean the vaccine isn’t working. It just means that the vaccine rollout is going very well.
We also need to remember that the UK vaccine rollout has consistently targeted those most at risk for COVID. The elderly and those with health problems that make them more vulnerable were the first to get vaccinated. Once vaccinated, these people (including me) are at much lower risk of COVID than they otherwise would have been – but they are still at risk.
This means that when we compare people hospitalized for the two vaccines with those who did not receive the two doses, we are not comparing the same. People who have received both vaccines are more likely to have been at greater risk for COVID in the first place. This makes them both more likely to be hospitalized and more likely to have already received their two doses of the vaccine.
Is COVID Different in People Who Have Been Vaccinated?
The latest data from Public Health England suggests that against the delta variant, which is now dominant in the UK, two doses of one of the vaccines available in Britain are estimated to provide 79% protection against symptomatic COVID and 96% against hospitalization.
We do not yet have clear estimates from Public Health England on the level of protection against deaths caused by the delta variant – luckily, this is in part due to the fact that deaths were relatively low during this third wave. United Kingdom.
But for the alpha variant, data from Public Health England estimates that the Pfizer vaccine is between 95% and 99% effective in preventing death from COVID-19, with the AstraZeneca vaccine estimated to be between 75% and 99% effective. The evidence we have so far does not suggest that the delta variant significantly changes this picture.
We still have a lot to learn about how people with both doses of the vaccine respond to infection with the virus. The UK COVID Symptom Study examines this. One of the key questions that remain is who is most at risk. Emerging data – published in a pre-publication, which has yet to be reviewed by other scientists – suggests that overweight or obese people, poorer people, and people with health conditions causing frailty appear to be more likely to become infected after receiving both injections.
The preprint also suggests that age itself does not appear to affect the chances of developing COVID after being vaccinated, nor does having a long-term illness like asthma, diabetes, or heart disease. – but we need more data on this to be sure. results.
Typically, the COVID Symptom Study found that people report the same COVID symptoms whether or not they have been vaccinated, but people who have been vaccinated have fewer symptoms over a shorter period of time. , which suggests a less serious illness. The most common symptoms reported in people who received both doses were headache, runny nose, sneezing, sore throat, and loss of smell.
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