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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.

Editor’s note: We updated this article on March 9, 2022 to better differentiate between data obtained by the overall review and data from one of the studies that the review covered.

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.

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The findings are available online in the UKHSA library.

This review synthesized evidence obtained from a rapid search undertaken on 12 January 2022 to identify primary studies related to the effectiveness of vaccination against long COVID. Its function was to provide more timely information for COVID treatment decisions when compared with standard systematic reviews that can take much longer.

As of December 2021, an estimated 2% of the U.K. population reported long COVID symptoms that sometimes lasted for more than 4 weeks after first contracting SARS-CoV-2.

As of January 2022, 16% of people in the U.K. eligible to receive the vaccine have not received a second dose. People in minoritized and marginalized groups have the lowest rates of vaccination and tend to have the highest rates of COVID-19.

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

The review included 15 local and international studies. Eight studies looked at the effects of vaccines that participants received before contracting SARS-CoV-2.

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

One particular study examined the effect of vaccination on long COVID symptoms in previously unvaccinated participants hospitalized with COVID-19.

Researchers followed these individuals to see if they remained unvaccinated or went on to receive a vaccine.

One month after vaccination, 23% of the participants reported improved symptoms compared to 15.4% of participants who remained unvaccinated, and 25.6% of people reported less worsened symptoms compared to 14.3% of unvaccinated participants.

One of the studies mentioned in the review was led by Daniel Ayoubkhani from the Office for National Statistics (ONS). Dr. Ayoubkhani examined the effect of vaccination on long COVID symptoms. 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.

This study 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%).

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.

The data gathered by the review 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 stated:

“This [review] 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.”

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