Vaccinated Patients Had Lower Rates of Long COVID After SARS-CoV-2 Infection

Post-COVID-19 condition, often called long COVID, affects 2% or more of patients recovering from SARS-CoV-2 infection. Now, one of the first large population studies to look at whether prior vaccination is effective in preventing the condition has come up with positive results. Here are more details.

GOTHENBURG, SWEDEN – Is timely vaccination against COVID-10 protective against so-called long COVID-19? A new Swedish study suggests that is the case.

The population-based cohort study published in BMJ sought to investigate the effectiveness of primary COVID-19 vaccination -- the(first two doses and first booster dose within the recommended schedule -- against post-covid-19 condition (PCC).

https://www.bmj.com/content/383/bmj-2023-076990

In the database, all adults with COVID-19, 589,722, first registered between Dec. 27, 2020, and Feb. 9, 2022, in the two largest regions of Sweden. University of Gothenburg-led researchers followed patients from a first infection until death, emigration, vaccination, reinfection, a PCC diagnosis (ICD-10 diagnosis code U09.9), or the end of follow-up on Nov. 30, 2022, whichever came first. Considered vaccinated were any patients who had received at least one dose of a COVID-19 vaccine before infection.

Defined as the primary outcome was a clinical diagnosis of PCC. Vaccine effectiveness against PCC was estimated using Cox regressions adjusted for age, sex, comorbidities (diabetes and cardiovascular, respiratory, and psychiatric disease), number of healthcare contacts during 2019, socioeconomic factors, and dominant virus variant at the time of infection.

Results indicate that, of 299 692 vaccinated individuals with COVID-19, 1201 (0.4%) had a diagnosis of PCC during follow-up, compared with 4118 (1.4%) of 290 030 unvaccinated individuals. C

“COVID-19 vaccination with any number of doses before infection was associated with a reduced risk of PCC (adjusted hazard ratio 0.42, 95% confidence interval 0.38 to 0.46), with a vaccine effectiveness of 58%,” the authors point out. “Of the vaccinated individuals, 21 111 received one dose only, 205 650 received two doses, and 72 931 received three or more doses. Vaccine effectiveness against PCC for one dose, two doses, and three or more doses was 21%, 59%, and 73%, respectively.”

The researchers suggest their results show “a strong association between COVID-19 vaccination before infection and reduced risk of receiving a diagnosis of PCC. The findings highlight the importance of primary vaccination against COVID-19 to reduce the population burden of PCC.”

Background information in the study notes that, shortly after the start of the pandemic, “reports emerged describing persistent symptoms among some people who had recovered from COVID-19, regardless of whether they had been admitted to hospital with the disease, often referred to as long covid or post-covid-19 condition (PCC). “

The researchers write that they previously found that 2% of adults with COVID-19 in Sweden received a diagnosis of PCC, but that studies using self-reported data usually found a higher incidence rate. Generally described symptoms of PCC include fatigue, dyspnea, cognitive impairment, headache, muscle pain, and cardiac abnormalities such as chest pain and palpitations.

Yet, few studies have evaluated the effectiveness of COVID-19 vaccines to prevent PCC in large population-based settings, they point out, noting that a recent systematic review concluded that receiving a COVID-19 vaccine before SARS-CoV-2 infection had a protective effect against PCC in 10 of the 12 included studies. The effect estimates (odds ratios and hazard ratios) range from 0.48 to 0.87 for any vaccine dose before infection, the researchers advise.