39% of non-hospitalized Covid patients did not neutralize B.1.351
Emerging SARS-CoV-2 variants of concern evade humoral immune responses from infection and vaccination
[Preprint.] We assessed the recognition of three variants of concern (B.1.1.7, B.1.351 and P.1) in cohorts of COVID-19 patients ranging in disease severity (n = 69) and recipients of the Pfizer/BioNTech vaccine (n = 50). Spike binding and neutralization against all three VOC was substantially reduced in the majority of samples, with the largest 4-7-fold reduction in neutralization being observed against B.1.351. While hospitalized COVID-19 patients and vaccinees maintained sufficient neutralizing titers against all three VOC, 39% of non-hospitalized patients did not neutralize B.1.351. Moreover, monoclonal neutralizing antibodies (NAbs) show sharp reductions in their binding kinetics and neutralizing potential to B.1.351 and P.1, but not to B.1.1.7.
SARS-CoV-2 variants, spike mutations and immune escape
In this Review, we summarize the literature on mutations of the SARS-CoV-2 spike protein, the primary antigen, focusing on their impacts on antigenicity and contextualizing them in the protein structure, and discuss them in the context of observed mutation frequencies in global sequence datasets.
Vietnam detects hybrid of Indian and UK Covid-19 variants
[Media report.] Authorities in Vietnam have detected a new coronavirus variant that is a combination of the Indian and UK Covid-19 variants and spreads quickly by air, the health minister said on Saturday. After successfully containing the virus for most of last year, Vietnam is grappling with a rise in infections since late April that accounts for more than half of the total 6,856 registered cases. So far, there have been 47 deaths.
SARS-CoV-2-specific memory B cells can persist in the elderly despite loss of neutralising antibodies
[Preprint.] Memory B cells (MBC) can provide a recall response able to supplement waning antibodies with an affinity-matured response better able to neutralise variant viruses. We studied a cohort of vulnerable elderly care home residents and younger staff, a high proportion of whom had lost neutralising antibodies (nAb), to investigate their reserve immunity from SARS-CoV-2-specific MBC. Class-switched spike and RBD-tetramer-binding MBC with a classical phenotype persisted five months post-mild/asymptomatic SARS-CoV-2 infection, irrespective of age. Spike/RBD-specific MBC remained detectable in the majority who had lost nAb, although at lower frequencies and with a reduced IgG/IgA isotype ratio.
Persistence of humoral immune response to SARS-CoV-2 up to 7 months post-infection: Cross-sectional study, South India, 2020-21
We conducted a cross-sectional study among recovered COVID-19 patients between November 10 and December 15, 2020 across all age groups in Chennai, India. IgG seropositivity against nucleo-capsid (NC) protein 15-30, 31-60, 61-90, 91-120, 121-150, 151-180 and 181-232 days after RT-PCR diagnosis was 83.2% (95%CI: 76.1% - 90.3%), 85.1% (95%CI: 78.2% - 92.1%), 75.7% (95%CI: 67.8% - 83.5%), 71.3% (95%CI: 62.5% - 80.1%), 58.2% (95%CI: 49.0% - 67.4%), 51.4% (95%CI: 41.9% - 61.0%), and 37.1% (95%CI: 28.3% - 45.9%) respectively. The IgG anti-NC, anti S1-RBD and neutralising antibody waned faster among the individuals with no to mild/moderate symptoms than individuals who had severe illness. In conclusion, findings of our study indicated that IgG antibodies against NC and S1-RBD waned over time but the neutralisation function of the antibody remained stable in majority of the COVID-19 infected patients till 7 months of post-infection.
On a lighter note: Meet the Ohio vaccine lottery’s $1 million winner: A 22-year-old who ‘thought it was a prank.’