Human vaccines & immunotherapeutics: news

Abstract

Two approved adenovirus-based vaccines (J&J and AstraZeneca) have been implicated in severe brain clots. The European Medicines Agency received reports of 169 cases following 34 million administered doses of the AZ vaccine and recommended its continued use, as the risk of dying from Covid-19 is far greater than that from rare adverse events. Nonetheless, Denmark has stopped using the vaccine, and the EU is considering to not extend contracts with J&J and AZ. Six cases of cerebral thrombosis have been reported in the US from ~7 million people who received the J&J vaccine. The Centers for Disease Control and Prevention is reviewing the data while the rollout of this vaccine has been paused. The World Health Organization (WHO) has called attention to a “shocking imbalance” in the distribution of Covid-19 vaccines around the world. Although the COVAX initiative has distributed 38 million vaccine doses to poorer countries, the rich ones still have a disproportionate share. “On average in high-income countries, almost one in four people have received a Covid-19 vaccine. In low-income countries, it is one in more than 500,” WHO Director General Tedros Adhanom Ghebreyesus said. Meanwhile, the inactivated vaccine CoronaVac (Sinovac) has been shown to be 50% efficacious in preventing infection by the hyper-transmissible SARS-CoV-2 strain P.1 in Brazil, where this lineage dominates. The efficacy rate is similar to that against the parent strain. Although much lower in its effectiveness than other vaccines in use, it still could slow the spread of Covid-19 in one of the worst affected countries. While most current vaccines require two doses to attain full protection in disease-naïve individuals, one dose might be sufficient in subjects who have had SARS-CoV-2 infection prior to vaccination. According to a report on the two marketed mRNA vaccines (Pfizer/BioNTech and Moderna), there is little benefit of receiving the second dose in previously infected people. Among other SARS-CoV-2 vaccines in development is another mRNA candidate MRT5500 (Translate Bio), which has shown immunogenicity and protective efficacy in mouse and primate models, and a recombinant vaccine, in which E. coli expresses a surface fusion peptide based on a conserved coronaviral sequence. This vaccine, which is easily produced and could solve many logistical hurdles, was protective in a porcine model. Personalized cancer vaccine was safe in an early trial