Lancet publishes interim data from two phase II clinical trials, one of the durability of protection from SARS-CoV-2 after two doses of CoronaVac, and the safety and immunogenicity of a third dose of the vaccine in adults ages 18 to over 60. Six months after primary vaccination, the researchers found that neutralising antibody responses dropped nearly to pre-vaccination levels. Giving a third dose 8 months later led to a strong boost in immunity, while administering it 2 months after the second dose did not induce comparable increases in neutralising antibody titres. Side effects from the third dose were no different from those of the previous two doses. Source

• GlaxoSmithKline issues a press release announcing that sotrovimab, a monoclonal antibody the company has co-developed with Vir Biotechnology, remained active against the Omicron variant in preclinical testing, which adds to “ …the growing body of preclinical evidence demonstrating that sotrovimab retains activity against all tested variants of concern.” Source

• USAID announces the US Government’s Initiative for Global Vaccine Access, which is specifically focused on scaling up support (such as bolstering cold chain supply and logistics, service delivery, vaccine confidence and demand, human resources, data and analytics, and local planning) for coronavirus vaccination in sub-Saharan Africa. The US is adding an additional $400 million to the over $1.3 billion it has already committed to vaccine readiness. Source

• A pre-print article assesses protective capacity of monoclonal antibodies and mRNA vaccines against the Delta and Omicron variants of SARS-CoV-2. Researchers tested monoclonal antibodies against the virus, and assessed neutralizing antibody responses to SARS-CoV-2, using blood from people who received two doses of Moderna’s coronavirus vaccine (at 6 or 0.5 months after last vaccination/booster), two or three doses of the Pfizer/BioNTech vaccine (at 6, 0.5 or 3 months after their last vaccination/booster), including people who had recovered from COVID-19, and people vaccinated with a mixed-dose regimen of the Oxford/AstraZeneca and Pfizer coronavirus vaccines. They found that the efficacy of mRNA vaccine-induced neutralizing antibodies was severely reduced against the Omicron variant, and those induced by the Oxford/AstraZeneca vaccine were ineffective, highlighting the importance of T cell responses for prevent serious illness, hospitalization and death from COVID-19 – and that Omicron is resistant to the monoclonal antibodies casirivimab and imdevimab. The authors suggested boosters, development of variant-specific vaccines and pre-treatment genotyping before treatment with monoclonal antibodies may be necessary. Source

• WHO updates its living guideline on COVID-19 treatment, recommending against convalescent plasma for patients with mild-to-moderate COVID-19. An expert panel looked at data from 16 clinical trials with 16,266 COVID-19 patients, finding no evidence of benefit in patients without severe illness. For patients with severe COVID-19, WHO recommends that convalescent plasma should only be used in clinical trials. Source

• The UK tightens restrictions for travelers as Omicron cases – some without links to international travel – rose from 160 on to 336 in just three days. Vaccinated visitors must be tested before their departure to the UK, and travelers from “red list” countries must also self-pay for 10 days of hotel quarantine and undergo two PCR tests. Source

• A pre-print paper from South African researchers looked at how the Omicron variant enters cells, and whether it can evade immune responses induced by Pfizer/BioNTech coronavirus vaccine and/or a previous SARS-CoV-2 infection. They found that the variant still uses the ACE-2 receptor, and that potency of vaccine-induced antibodies decreased significantly, to levels that may not protect against breakthrough Omicron infections, while people who recovered from COVID-19 and were vaccinated had more potent responses against Omicron. The authors suggested that “…previous infection, followed by vaccination or booster is likely to increase the neutralization level and likely confer protection from severe disease in Omicron infection.” Source

• WHO estimates that one in 10 people across Europe and Central Asia will have been infected with SARS-CoV-2 by the end of 2021, and urges governments to step up their vaccination campaigns. Source

• Medicago and GlaxoSmithKline issue a press release to announce data from an over 24,000-person phase III trial of their plant-based, adjuvanted coronavirus vaccine which relies on virus-like particles. The vaccine’s overall efficacy was 71 percent, with slight variant-based differences (such as 75.3 percent efficacy against mild-moderate or severe COVID-19 caused by the Delta variant, and 88.6 percent against the Gamma variant; there were 12 cases of the Alpha, Lambda and Mu variants, among unvaccinated participants only). The study was conducted before Omicron began to circulate. There were no cases of severe COVID-19 among vaccinated study participants, versus a “small number” among placebo recipients. No serious adverse events occurred; vaccine side effects were mild-to-moderate. Medicago plans to seek regulatory approval from Health Canada as part of its rolling submission. Source

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