Kinetics of successive SARS-CoV-2 infections

*Important Notices: medrex sib We publish a non-peer-reviewed, preliminary scientific report and should not be viewed as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.

In a recent study posted on medrex sib* In a preprint server, researchers compare the viral dynamics of successive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections.

study: Viral dynamics of sequential SARS-CoV-2 infection. Image Credit: Limbitech / Shutterstock.com

Does COVID-19 prevent future infections?

As of November 2022, approximately 65% ​​of the US population has been infected with SARS-CoV-2 twice. Some evidence suggests that previous infections reduce reinfection risk to some extent, but other studies report that initial infection limits recovery from coronavirus. Disease 2019 (COVID-19). These differing findings may be due to bias when differences in vaccination status, comorbidities, and exposure history were not considered.

Controlling for these factors is difficult due to heterogeneous interventions. However, assessing viral dynamics at the individual level can adjust for such biases. Viral dynamics offer a unique opportunity to understand the impact of initial infection on subsequent infections and to translate these findings into public health/medical guidance.

The impact of variant type and vaccination on viral dynamics is well established. Delta infections are characterized by higher peak viral concentrations than alpha/omicron infections. Nevertheless, the effects of infection-induced immunity on peak levels of viral growth, clearance, and reinfection are poorly understood.

About research

In the current study, researchers are evaluating the viral dynamics of SARS-CoV-2 infection among National Basketball Association (NBA) staff, players, and officials. The NBA conducted COVID-19 surveillance from March 11, 2020 through July 28, 2022. This includes frequent testing and clinical evaluations consisting of symptom tracking and case diagnosis as part of a wellness program.

Reverse transcription quantitative polymerase chain reaction (RT-qPCR) tests were performed on oropharyngeal and anterior nasal swabs. SARS-CoV-2 lineages were assigned after whole-genome sequencing.

Vaccination status and age of participants were recorded. Vaccination status was assigned at the first positive test for each infection. The authors identified a well-documented infection. This was defined as a cycle threshold (Ct) value less than 32 in at least one test and less than 40 in three tests.

A hierarchical piecewise linear model was fitted to the SARS-CoV-2 concentration measurements on a logarithmic scale. This model captured viral growth time, clearance time, and peak concentration.

We adjusted the model fit for age by applying the Hamiltonian Monte Carlo algorithm. The researchers also examined whether the kinetics of SARS-CoV-2 Omicron BA.1/BA.2 infection differed between his first and his second infection.

Differences in viral kinetics between first and second infections in subjects with non-Omicron first infections and Omicron second infections were also determined. In addition, the researchers examined whether relative individual-level viral dynamics persisted after infection.

Pearson correlation was used for sensitivity analysis, whereas Spearman correlation was used to determine the relative persistence of virus dynamics attributes across infections.

findings

A total of 3,346 infections were reported among 3,021 people. Of these, there were 1,989 well-documented infections, of which 193 were secondary infections.

In SARS-CoV-2 Omicron infection, previous infection correlated with faster clearance on average of 4.9 days compared to 7.2 days for Omicron infection without previous infection.

In addition, previously infected vaccine-boosted participants had an infection clearance time approximately 5.1 days shorter than those who had no history of infection. Peak virus concentrations and growth times were not significantly different between the non-omicron first infection caused by the omicron variant and her second infection.

Notably, the clearance time was approximately 5.1 days compared to approximately 8.8 days for the first infection, which was shorter for the second infection. Study participants in this group who were vaccinated between infections had slightly faster clearance rates for their second infection than those who were not vaccinated between infections. There was no evidence that variant category influenced viral dynamics in later Omicron infections.

Among participants who experienced two well-documented infections, those who had a relatively fast clearance rate on the first infection were more likely to have a shorter clearance time on the second infection, The opposite was also true.

There was weak evidence that individual proliferative time was conserved. However, individual peak viral concentrations were not maintained after infection.

Conclusion

A current study showed that for people with multiple infections, the second infection healed much faster than the first, especially if they received interventional vaccination. The SARS-CoV-2 variant/strain of the initial infection did not affect viral kinetics of subsequent Omicron infections. Nevertheless, relative individual-level clearance rates persisted across infections.

Although prior infection history and vaccination may modulate viral dynamics, some additional immunological mechanisms conserved across infections may determine immunity to the virus. However, it remains to be elucidated whether this relative ability to clear infection can be generalized to other infections. coronavirus Or pathogen.

*Important Notices: medrex sib We publish a non-peer-reviewed, preliminary scientific report and should not be viewed as conclusive, to guide clinical practice/health-related actions, or to be treated as established information.