COVID vaccine after infection may decrease long COVID symptoms

Post-COVID, or "long COVID," remains a challenging condition to manage, as the evidence base regarding effective treatment options remains limited. An observational cohort study from the United Kingdom (UK), however, has found that COVID-19 vaccination after COVID-19 infection may decrease these frustrating symptoms.

This study's researchers used data from a large UK database, the COVID-19 Infection Survey. Since April of 2020, UK survey workers visited the home of every person with documented COVID-19 infection and requested permission to enroll them in the survey along with permission to return regularly (weekly for the first month and then monthly thereafter) to test for reinfection and ask about persistent symptoms. The observational cohort study used this database to identify persons who both answered a survey question about long COVID symptoms and had received a COVID-19 vaccine after their acute infection.

The observational cohort researchers identified 28,356 persons from this survey who had both received a COVID-19 vaccination at some point after COVID-19 infection and responded to a question regarding the presence or absence of long COVID:

 [The] first vaccine dose was associated with an initial 12.8% decrease (95% confidence interval −18.6% to −6.6%, P<0.001) in the odds of long covid, with subsequent data compatible with both increases and decreases in the trajectory (0.3% per week, 95% confidence interval −0.6% to 1.2% per week, P=0.51). A second dose was associated with an initial 8.8% decrease (95% confidence interval −14.1% to −3.1%, P=0.003) in the odds of long covid, with a subsequent decrease by 0.8% per week (−1.2% to −0.4% per week, P<0.001)

While these results sound promising, the researchers note that median follow-up after a second dose was only 67 days; it's also important to remember that cohort studies can only establish correlation, not causation. Still, this study might help us persuade persons who are un- or under-vaccinated for COVID-19 to receive a vaccine after a COVID-19 diagnosis. The benefit to vaccination after acute COVID-19 infection may extend beyond ameliorating long COVID; As Dr. Lin wrote on the blog earlier this year, two previous cohort studies suggest that vaccination further reduces the risk of subsequent COVID-19 infection compared to the "natural" immunity that results from infection alone. Patients with COVID-19 can be vaccinated as soon as they complete isolation unless they received monoclonal antibodies or convalescent plasma (then the Centers for Disease Control and Prevention recommends waiting for 90 days). 

The AFP By Topic on COVID-19 includes this editorial on long COVID along with this Curbside Consultation on COVID-19 vaccine hesitancy, and the AAFP is also offering free CME on "Managing Effects of Long COVID" if you'd like to learn more.