Post-COVID-19 symptoms 6 months after acute infection among hospitalized and non-hospitalized patients. 2021, Peghin et al

Abstract

Objectives
To assess the prevalence of and factors associated with Post-Coronavirus Disease 2019 (COVID-19) syndrome six months after the onset.

Methods
A bidirectional prospective study. Interviews investigated symptoms potentially associated with COVID-19 six months after the disease onset of all consecutive adult in- and out-patients with COVID-19 attending Udine Hospital (Italy) from March to May 2020. IgG antibodies against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) were also evaluated six months after the onset of symptoms, at the time of the interview.

Results
A total of 599 individuals were included (320 female, 53.4%; mean age 53 years, SD 15.8) and interviewed 187 days (22 SD) after the onset. The prevalence of post-COVID-19 syndrome was 40.2% (241/599). The presence of IgG antibodies was significantly associated with the occurrence of post-COVID-19 syndrome (OR 2.56, 95% CI 1.48–4.38, p = 0.001) and median SARS-CoV-2 IgG titres were significantly higher in long-haulers than in patients without symptoms (42.1, IQR 17.1-78.4 vs. 29.1, IQR 12.1-54.2 kAU/L, p = 0.004). Female gender (OR 1.55, 95% CI 1.05–2.27), a proportional increase in the number of symptoms at the onset of COVID-19 (OR 1.81, 95% CI 1.59–2.05) and ICU admission OR 3.10, 95% CI 1.18–8.11) were all independent risk factors for post-COVID-19 syndrome. The same predictors also emerged in a subgroup of 231 patients with the serological follow-up available at the time of the interview alongside the proportional increase in anti-SARS-CoV-2 IgG (OR 1.01, 95% CI 1.00–1.02, p = 0.04).

Conclusions
Prospective follow-up could be offered to specific subgroups of COVID-10 patients, to identify typical symptoms and persistently high anti-SARS-CoV-2 IgG titers as a means of early detection of post-COVID-19 long-term sequelae.

Open access, https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(21)00281-0/fulltext

 

My limited understanding of the immune system says first 30 days of infection, one's IgM antibodies are at play. If the infection is not resolved, those antibodies give way to IgG antibodies.

As our medical culture is primarily focused on acute infections, clinicians are taught that IgGs are just signs of an old but resolved infection. IgG positives are just immune memory at play.

But they are plenty of examples where this general medical short hand is wrong, that in fact being IgG positive is highly suggestive of persistent infection. Moreover, confirmatory tests in some of these cases - like PCR - are frequently limited in utility for a number of various reason (e.g. the pathogen is tissue tropic).