Covid-19 vaccination only partially reduces the risk of long Covid symptoms, as well as other comorbidities, according to a study published in Nature Medicine—suggesting that a different approach is needed to effectively combat long Covid.
Study details and key findings
For the study, researchers at the VA St. Louis Healthcare System analyzed data from Jan. 1, 2021, to Oct. 31, 2021, in the Department of Veterans Affairs national health care databases. In total, there were 33,940 individuals who had been vaccinated and developed a breakthrough infection, and 4,983,491 controls who had no record of a positive Covid-19 test.
Compared with the controls, patients with breakthrough infections had a more than two-fold higher risk of pulmonary complications and coagulation/hematologic disorders, as well as a two-fold higher risk of fatigue 30 days post-infection. In addition, the researchers found these patients had an almost two-fold higher risk of death, as well as higher risks of cardiovascular, gastrointestinal, kidney, mental health, musculoskeletal, and neurologic conditions compared with the controls.
However, patients with breakthrough infections still had lower risks of lingering Covid-19 symptoms and death than unvaccinated patients. In particular, the researchers noted patients with breakthrough infections had a "consistently reduced risk" of hematologic/coagulation disorders and pulmonary disorders.
Overall, vaccinated individuals in the study had a 15% reduced risk of having long Covid six months after their initial Covid-19 diagnosis, the Washington Post reports.
Only individuals with a positive Covid-19 test were included, meaning there could have been many people who had Covid-19 but were not tested. In addition, the VA population is at least 90% men, limiting the study's generalizability. The researchers also said it's possible that some confounding variables may not have been accounted for.
According to the researchers, the findings suggest that being vaccinated before getting infected by the coronavirus may offer "only partial protection" against lingering symptoms and that relying on vaccination alone may not be enough to reduce the effects of long Covid.
"This was disappointing," said Ziyad Al-Aly, lead author of the study and chief of research and development service at VA Saint Louis Health Care System. "I was hoping to see that vaccines offer more protection, especially given that vaccines are our only line of defense nowadays."
"Getting COVID-19, even among vaccinated people, seems almost unavoidable nowadays," Al-Aly added. "Now that we understand that COVID-19 can have lingering health consequences even among the vaccinated, we need to move toward developing mitigation strategies that can be implemented for the longer term since it does not appear that COVID-19 is going away any time soon."
According to Al-Aly, current methods of protection—including vaccination, masking, and social distancing—are "not sustainable," and a more layered approach is needed to protect people from infection and the subsequent risk of long Covid.
"Our current approach will likely leave a large number of people with chronic and potentially disabling conditions that have no treatments," he said. "We need to urgently develop and deploy additional layers of protection that could be sustainably implemented to reduce the risk of long COVID." (Choi, The Hill, 5/25; Walker, MedPage Today, 5/25; Cha, Washington Post, 5/25)