[UPDATED] Vaccination + Long COVID

Mar 10, 2022

New research out of the UK  suggests that “COVID-19 vaccination is associated with reduced risk of Long COVID.”

  • An additional UK-based case-control study of 1.2 million users of a COVID symptom tracker app showed that there were lower odds of symptoms lasting 28 days or more in individuals who had received two vaccine doses – the risk of developing Long COVID was reduced by around 50% in those who were double vaccinated.
  • The UK Health Security Agency released a rapid evidence briefing citing fifteen studies identified that reported on the effectiveness of vaccination against Long COVID
    • Six studies showed that those who received one or two vaccine doses before coronavirus infection were less likely to develop symptoms of Long COVID after infection.
    • Three studies found that most people reported an improvement in Long COVID symptoms after vaccination, either immediately or over several weeks long.
    • Two studies showed fully vaccinated people were less likely than unvaccinated people to develop medium- or long-term symptoms (fatigue, loss of smell, etc).
  • A study in Israel conducted between July and November 2021 showed that patients who were fully vaccinated were 64% less likely to report fatigue, 54% less likely to report headaches, 57% less likely to report weakness, and 68% less likely to report muscle pain than unvaccinated counterparts. 
  • At a minimum, the vaccine reduces the impact of Long COVID by preventing COVID infection in the first place. It may also be possible that the vaccine prevents the virus from remaining in the body long enough to cause excessive damage

[Original post from January 13, 2022] Although the WHO released its first clinical definition of Long COVID in October of 2021, there is still no definitive agreement on what it is or how to officially diagnose it–a common pain point for clinicians, patients and insurers alike. The majority of scientific literature cites the CDC’s definition, often describing a syndrome with persisting symptoms at least 4 weeks following a COVID-19 diagnosis. 

According to recent studies conducted in the UK, 7%-18% of those who contracted COVID-19 reported lingering symptoms for at least 5 weeks. Some studies also show that the more severe the initial COVID-19 case, the higher the risk of developing Long COVID. While some of the persisting symptoms can be mild, others can be extremely debilitating leading patients to request special work accommodations. Indeed, the ADA has ruled that Long COVID can be a disability

Vaccination has become a useful tool in tackling the virus, with research proving its effectiveness against infection, hospitalization and death following a COVID-19 infection. However, the research is less clear as to whether vaccination can prevent Long COVID or provide symptomatic relief after the initial infection. 

Vaccination post-infection: a relief in symptoms for long-haulers? 

Emerging research has shown that vaccination may be effective in improving Long COVID symptoms. In other words, some long-haulers report seeing a relief in their symptoms after receiving a COVID-19 shot. The Long COVID initiative team reviewed recent articles and publications on the topic of Long COVID and vaccinations and found the below, sometimes contradictory, highlights:

  • A UK-based study published in October 2021, reports that participants who were previously infected with COVID-19 and received a first dose of the vaccination were 13% less likely to report symptoms of Long COVID. A second vaccine dose provided an additional 9% decrease in the risk of developing Long COVID. 
  • Another study shows that being vaccinated may lower a patient’s risk of several–but not all–Long COVID symptoms. However, some pre-print studies seem to find that Long COVID occurs at the same rate in vaccinated and unvaccinated individuals and that vaccines do not protect against Long COVID. 
  • A Yale study following a dozen of long-haulers prior to their vaccination, then 6 and 12 weeks after their vaccination by Dr. Akiko Iwasaki finds that as many as 40%-60% of those who were vaccinated after their infection said they experienced some relief from their symptoms, with some stating they felt full relief from brain fog or shortness of breath. 
  • A pre-print study from the Lancet following 812 long-haulers for a month indicates that after receiving the vaccination, 57.9% of respondents reported an improvement in symptoms. However, it seems that around 25% report no differences in their symptoms and around 20% report symptom worsening
  • This same study indicates that improvement in symptoms may be linked to receiving an mRNA vaccine (e.g. Pfizer-BioNTech or Moderna) vs. an adenoviral vector vaccine (e.g. Oxford/AstraZeneca). 
  • Some long-haulers report no difference in symptom severity after being vaccinated while Dr. Iwasaki notes that about 20% feel worse after vaccination. 
  • It is still unclear why some patients report improving or worsening conditions post-vaccination. 

How might the vaccine help long-haulers? 

If there is a beneficial link between vaccination and the relief of Long COVID symptoms, researchers still cannot explain why, from a physiological point of view, that might be the case. Perhaps the vaccine helps the immune system resist residual virus or dampens potentially harmful immune responses? 

What is the takeaway?  

Two years into the pandemic and a year since the start of the vaccine roll-out, it is evident that vaccines help prevent people from developing severe COVID-19 and dying from the virus. Vaccines prevent hospitalizations (73% less likely to be hospitalized) and lower acute symptoms (31% less likely). Protecting people from contracting Acute COVID-19 will subsequently keep them from developing Long COVID. 

However, when a breakthrough infection does occur–i.e. when a fully vaccinated individual becomes infected with COVID-19–vaccination may significantly decrease the risk of developing Long COVID, but may also have no effect on it at all. The general takeaway from available research is that a large number of Long COVID patients report an improvement in their symptoms but the relationship between vaccination and Long COVID prevention remains unclear. 

For inquiries related to the Long COVID Initiative, please contact long_covid_initiative@brown.edu