Science Says... Natural Immunity Following Severe COVID-19 is Superior
Survivors of Severe COVID-19 Take Heart. More data needed on Mild Cases Due to Likelihood of PCR False Positives.
“We found that NAb against the WT virus persisted in 89% and S-IgG in 97% of subjects for at least 13 months after infection.”
As measured by neutralizing antibody assays, immunity to SARS-CoV-2 from vaccination wanes after 3-4 months.
This study in the European Journal of Immunology has some good news: Survivors of severe COVID-19 from had very high immunity against Delta 13 months after their initial infection with earlier variants.
The study was conducted on 2586 subjects ≥18 years of age whose native language was Finnish or Swedish who lived within five selected hospital districts in Finland and with a “PCR-confirmed COVID-19 diagnosis”.
The authors examined neutralizing antibody levels (Nab) against Wild-Type (Wuhan), Alpha, Beta and Delta proteins, studying both the Spike glycoprotein (S-protein)) and the viral nucleoprotein (N-protein)) at 8 and 13 months following infection.
The Spike protein Nab measured as antibodies against two epitopes) was higher at 13 months than against the nucleoprotein (N-protein), as would be expected given the easier access of the spike protein to our immune system. That said, N-protein NAb production was still very high.
The greatest result, which is very, very welcome, came when the authors examined the Nab is subgroups. They looked at NAbs in people who had mild infections and those who had severe COVID-19.
Those who had severe COVID-19 have the highest Nabs against both proteins. And that’s excellent news for people who had to suffer severe COVID-19.
Here’s their table for the S protein IgG (immunoglobulin) and neutralizing antibodies
People with mild infections, however had lower overall protection percentagewise from any Nabs against more recent variants:
This result, however, could be due to false positives in the PCR tests in the mild cases.
Note also that people who do not have Nab after 13 months, however, most likely have immune memory cells (B-cells and T-cells).
Here’s the study (first page is an ad, don’t worry it’s the correct link):
Haveri A, Ekström N, Solastie A, Virta C, Österlund P, Isosaari E, Nohynek H, Palmu AA, Melin M. Persistence of neutralizing antibodies a year after SARS-CoV-2 infection in humans. Eur J Immunol. 2021 Dec;51(12):3202-3213. doi: 10.1002/eji.202149535. Epub 2021 Oct 8. PMID: 34580856; PMCID: PMC8646652.