A recent study published in the the Lancet gave us our first good look at how vaccination can affect the likelihood of long COVID. And the good news is that vaccination appears to significantly reduce chances! We know very well by now that vaccination reduces your chance of infection, and if you don’t get infected you have a 0% chance of long COVID! But what if you do have a breakthrough case?
Ultimately it was found that if vaccinated individuals with breakthrough cases were:
⁃ 94% more likely to show no symptoms (asymptomatic)
⁃ 31% less likely to have 6 or more total symptoms during active infection
⁃ 49% less likely to have symptoms that last more than 28 days
This study included over 1.2 million individuals from Dec 2020 to July 2021 who reported data in a COVID Symptom Study app. Just 6,030 participants reported testing positive for COVID-19 (after 1 or 2 doses), which is a breakthrough percentage of 0.5%. Of these, 3,825 tested positive after just 1 dose but continued reporting past 14 days, and 906 tested positive after 2 doses and also had extended reporting data. Each of these participants were matched to unvaccinated individuals who tested positive during the same timeframe that had similar baseline characteristics. From here, odds ratios could be calculated to analyze how symptom severity and duration compared between groups.