Vaccines Halve Chances of Long Covid, Study Finds

New research from the UK is among the first to examine the potential risk of experiencing persistent symptoms after a case of covid-19 in people who have been vaccinated, a phenomenon often known as long covid. The study suggests that vaccinated people who are infected are half as likely to show lasting symptoms as unvaccinated people. It is important to note that this risk reduction is in addition to the protection against the symptoms of covid-19 already provided by the vaccination.

The data from this new research, published Wednesday in The Lancet Infectious Diseases, comes from the COVID Symptom study: a long-running project that has tried to track the spread of the pandemic with a free mobile app, through which people in the UK are encouraged to report any covid-like symptoms they experience and other relevant details, including whether they have tested positive for the virus and their vaccination status. The app launched in March 2020 and there are said to be around 4.5 million unique users. In the UK, people have access to vaccines developed by Pfizer / BioNTech, Oxford / AstraZeneca and Moderna.

The researchers compared the results of about one million users who reported being partially and / or fully vaccinated with a control group of unvaccinated users. As of July 2021, about 8,000 of those vaccinated have reported confirmed infection (less than 1% of the total sample), with only about 2,000 reporting infection a week or more after the second dose. Compared with unvaccinated and infected people, vaccinated people were significantly less likely to report needing hospitalization, reported having no symptoms more often, and reported having fewer symptoms on average when they became ill. Only about 5.2% of fully vaccinated and infected people reported experiencing symptoms beyond 28 days, compared to 11.4% of the control group, indicating that the chances of having these symptoms in the long term were reduced by 47%.

“Vaccinations massively reduce the chances that people will long become covid in two ways. First, by reducing the risk of symptoms by 8 to 10 times, and then halving the chances of an infection turning into a long covid, if that happens, ”study author Tim Spector, researcher at King’s College London and principal investigator of the project, said in a declaration published by the university. “Regardless of the duration of the symptoms, we find that the infections after two vaccinations are also much milder, so the vaccines really change the disease and for the better. “

The study is one of the first to attempt to measure the possible prevalence of long covid in breakthrough infections. So it is possible that this is not the last word on how often this can happen. In July, for example, a study of healthcare workers in Israel find that 19% of people with breakthrough infections had symptoms that persisted for more than six weeks. Likewise, however, the chances of getting an infection in the first place were low (about 2% in the group of 1,500 people who were tested regularly).

Long-term covid studies in general have found variable prevalence rates among survivors, ranging from 10% to 30%. These estimates are further complicated by the fact that some people may experience many symptoms closely related to a long covid, such as mental and physical fatigue, after having had others. respiratory infections, while many people may have these symptoms for no clear reason.

While the exact numbers may fluctuate, it seems fair to say that vaccines offer significant but not complete protection against the worrying possibility of a long covid.