Coronavirus (Covid-19)

Emerging omicron subvariants express additional spike mutations that escape detection by neutralizing antibodies elicited by the current vaccines. Heterotypic chimeric RBD dimers elicit neutralizing antibodies in mice.

In a group of patients undergoing hemodialysis who had received four previous inoculations of SARS-CoV-2 vaccines, a fifth injection of a bivalent mRNA vaccine boosted serum neutralizing activity against omicron variants.

Interferons can stimulate early antiviral immunity. In this platform trial, a single dose of pegylated interferon lambda given early was associated with decreased progression to more severe Covid-19.

Participants who had received three doses of BNT162b2 vaccine received either a fourth dose or a bivalent vaccine containing BA.4–BA.5 mRNA; the latter group had higher neutralization against omicron variants.

Boosters of adjuvanted NVX-CoV2373 protein vaccine led to increasing neutralizing titers of antibody specific for the ancestral strain and omicron variants. Whether the elicited antibodies protect against infection is unclear.

A test-negative, case–control study in Qatar showed that previous infection with pre-omicron strains of SARS-CoV-2 conveyed little protection against reinfection with BA.2.75, but more recent previous omicron infection conferred higher protection.

In a small study, a bivalent mRNA vaccine targeting omicron BA.4–BA.5 sublineages resulted in similar neutralization of other SARS-CoV-2 variants as a fourth dose of a monovalent mRNA vaccine.

BQ.1.1 and XBB.1 neutralizing antibody titers were lower than those against wild-type strain after boosters in vaccinated and previously infected persons. Both variants expressed the R346T spike mutation.

One or two monovalent vaccine boosters showed a large decrease in neutralization activity against omicron subvariants. The BA.5-containing bivalent booster improved neutralizing activity against all omicron subvariants.

Neither bebtelovimab nor any mAb combinations tested neutralized the SARS-CoV-2 omicron subvariants BQ.1.1 and XBB, but remdesivir, molnupiravir, and nirmatrelvir were efficacious against both in vitro.

Researchers report that antiviral agents remdesivir, molnupiravir, and nirmatrelvir and monoclonal antibodies bebtelovimab and imdevimab retain effectiveness against the BA.4.6 subvariant in vitro.

This documentary video explores the controversies surrounding masks throughout the centuries leading up to the recent Covid-19 pandemic.

Among school districts in the greater Boston area, the lifting of masking requirements was associated with an additional 44.9 Covid-19 cases per 1000 students and staff during the 15 weeks after a statewide masking policy was rescinded.

Serum from persons who received a booster dose with the omicron sequence–containing mRNA-1273.214 vaccine showed cross-neutralization activity against omicron variants that are not components of the vaccine.

A study of the neural effects of brain fog after mild SARS-CoV-2 infection shows neuroinflammation in a mouse model, identifies a candidate biomarker, and provides a framework for further study.

Although a third vaccine dose showed an improved and sustained level of protection as compared with a second dose, the improvement in immunity from a fourth dose was smaller and had waned completely by 13 weeks after administration.

A 57-year-old woman with major depressive disorder and Covid-19 was hospitalized for treatment with oxygen, remdesivir, and dexamethasone. Ten days later, she began to have delusions that she was dead. What is the diagnosis?

Unvaccinated persons without previous Covid-19 had the highest risk of omicron infection; those who had been infected after emergence of the delta variant and had received three mRNA vaccine doses were the most protected.

In a randomized, placebo-controlled trial involving children 6 months to 5 years of age, the mRNA-1273 vaccine was shown to be safe, and the elicited antibody responses were similar to those in young adults.

Among Israeli adolescents between 12 and 15 years of age who received the BNT162b2 vaccine, 9 cases of mild myocarditis were observed, mainly after the second dose.

Evidence from this cohort study suggests that an earlier infection with pre-omicron SARS-CoV-2 before a first omicron infection may broaden the immune response against a future reinfection challenge.

Neutralization titers against omicron subvariant BA.4.6 were lower by a factor of 2 to 2.7 than titers against subvariants BA.4 and BA.5 induced by infection or vaccination against SARS-CoV-2.

Neutralizing autoantibodies to interleukin-1 receptor antagonist were present in the circulation of the majority of patients with biopsy-confirmed myocarditis after SARS-CoV-2 vaccination.

In this study, SARS-CoV-2 infection before vaccination was found to elicit mucosal IgA, which protects against infection. Vaccines inducing mucosal immunity may be important for preventing infection.

A booster dose of mRNA-1273 after the initial two-dose vaccination resulted in neutralization titers against the BA.2.75 variant that were similar to those against BA.1 and BA.2 and higher than those against BA.5.

In a 6-month study in children while omicron was dominant, previous SARS-CoV-2 infection and the BNT162b2 vaccine lowered the risks of infection, hospitalization, and death, but protection against omicron declined rapidly.

Cases of SARS-CoV-2 viral load rebound have been reported after a 5-day course of nirmatrelvir–ritonavir. Investigators evaluating viral load rebound among high-risk patients found similar results with nirmatrelvir–ritonavir and placebo.

In this report, investigators describe 13 cases of SARS-CoV-2 rebound infection occurring approximately 5 to 9 days after completion of a 5-day course of nirmatrelvir–ritonavir.