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New research finds that vaccination reduces the risk of developing long COVID. Rory Doyle/Bloomberg via Getty Images
  • A new study investigates whether receiving two doses of a coronavirus vaccine before a SARS-CoV-2 infection is associated with reduced long COVID symptoms after 12 weeks.
  • COVID-19 vaccines given prior to infection appear effective in resisting long COVID following breakthrough infections or infection after two doses.
  • These findings have relevance for United Kingdom public health initiatives aimed at reducing the prevalence of long Covid in the U.K. population, especially in disadvantaged communities where prevalence is higher.

The Centers for Disease Control and Prevention (CDC) describe long COVID in the following terms:

“Post-COVID conditions are a wide range of new, returning, or ongoing health problems people can experience 4 or more weeks after first being infected with the virus that causes COVID-19. Even people who did not have COVID-19 symptoms in the days or weeks after they were infected can have post-COVID conditions. These conditions can present as different types and combinations of health problems for different lengths of time.”

The UK Health Security Agency (UKHSA) recently undertook a rapid evidence review to determine the effects of vaccination levels on the development of long COVID syndrome or post-COVID symptoms in the U.K.

Daniel Ayoubkhani of the Royal Statistical Society, London, is the principal statistician who undertook this study for the UKHSA.

The findings, which have not yet undergone peer review, appear on the preprint server MedRXiv.

This review synthesized evidence obtained from surveys dated April 2020 to November 2021. Its function was to provide more timely information for COVID treatment decisions when compared with standard systematic reviews that can take much longer.

Before the current data review, it was unclear whether protection from two anti-COVID vaccine doses before a SARS-CoV-2 infection would reduce the likelihood of developing long COVID symptoms.

The data suggested that people vaccinated with one or two doses of the Pfizer, Astra-Zeneca, or Moderna vaccines, or one dose of the Janssen vaccine (Johnson & Johnson), before infection were half as likely to develop symptoms of long COVID following infection as people who received one dose or were unvaccinated.

The results showed that an estimated 2% of the U.K. population reported long COVID symptoms that sometimes last for more than 4 weeks after initial SARS-CoV-2 infection.

As of January 2022, 16% of people in the U.K. eligible to receive the vaccine have not received a second dose. Vaccine coverage is the lowest in minoritized and marginalized groups, which also tend to have the highest infection rates.

Researchers administered a COVID-19 Infection Survey to participants aged 18–69 years who tested positive for the SARS-CoV-2 virus between April 2020 and November 2021.

The review included 15 local and international studies and comprised 3,090 double-vaccinated participants with a mean age of 49 years: 54% were female, and 92% were white. The average follow-up time from infection was 96 days.

In the survey, people who were double-vaccinated 14 or more days before infection were compared with those who received one dose or were unvaccinated at the time of infection.

Among the participants, 294 double-vaccinated participants reported long COVID symptoms (prevalence 9.5%) compared with 452 unvaccinated ones (14.6%).

The effectiveness of vaccines against most long COVID symptoms was highest in participants aged 60 years and over and lowest for people aged 19–35 years.

Eight studies looked at the effects of vaccines given to participants before infection with SARS-CoV-2.

Those who received two COVID-19 vaccinations before infection were associated with a 41% decrease in the odds of developing long COVID symptoms 12 weeks later, relative to not being vaccinated at the time of infection.

Seven studies reported on unvaccinated people who experienced long COVID symptoms and then received vaccinations.

These participants reported an improvement in symptoms (23.2%) over people who remained unvaccinated (15.4%), either immediately or over many weeks.

This study is preprinted and not peer-reviewed, and the information it presents is obtained from a government survey and not live interviews. This survey correlated peoples’ vaccination status with only specific symptoms and diagnoses.

The data did extend previous research and showed that the risk of developing long COVID symptoms in double-vaccinated people was approximately half of those who were unvaccinated.

Medical News Today spoke with Dr. Davey Smith, professor of medicine, infectious disease specialist, and chief of the department of Infectious Diseases and Global Public Health at UC San Diego in La Jolla.

Prof. Smith’s remarks were in line with the authors of the study. He stated:

“This study provides good evidence that having preexisting immunity with vaccination before getting COVID-19 gives some protection from long COVID. Even if the COVID-19 vaccines cannot fully protect from infection, at least they strongly protect from bad outcomes like hospitalization and death during the acute infection, and now it seems they also offer some protection from long COVID.”

It is essential to understand the role of vaccines to enable better and more informed decision-making related to public health and vaccine uptake in the U.K. population.

The study authors acknowledge that more research and longer follow-up are needed. The analysis should consider the impact of booster doses and implications of the Omicron variant on the current COVID-19 landscape.

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