An analysis of 602 community contacts of 471 covid-19 index cases indicates that the secondary attack rate (SAR) for household contacts exposed to the delta variant is 25% in fully vaccinated individuals, compared to 38% in unvaccinated individuals.
A study of 32 million adults in England has shown a small increase in the risk of suffering from Guillain-Barré syndrome and Bell's palsy, two neurological conditions, after receiving AstraZeneca's vaccine. There was also an increased risk of stroke after receiving Pfizer's vaccine. However, according to the paper, these side effects are rare and the chances of suffering them are much higher after SARS-CoV-2 infection.
Two studies, one published in The New England Journal of Medicine and the other, the CDC's Morbidity & Mortality Weekly Report (MMWR), find that vaccination against COVID-19 effectively protects children and adolescents aged 12-18 years from both infection and severe disease. Both papers cover periods when the more transmissible Delta variant was dominant. Paediatrician Ángel Hernández Merino assesses these results.
A study published in Science Translational Medicine shows that pregnant women are more dependent on a second dose of vaccine to develop a full immune response. The work sheds light on how pregnancy affects immunity against SARS-CoV-2, a question still little studied. Obstetrician Mar Gil stresses the importance of getting pregnant women vaccinated, and of their inclusion in clinical trials.
A study of more than 700,000 people in Sweden analysed the effectiveness of the heterologous schedule, combining the AstraZeneca vaccine with another dose of a messenger RNA vaccine, with the traditional homologous schedule, consisting of two doses of AstraZeneca. The results showed increased protection against SARS-CoV-2 infection when two different vaccines were combined.
The European Medicines Agency issued its recommendations yesterday afternoon regarding the administration of a third dose of the Comirnaty (Pfizer/BioNTech) and Spikevax (Moderna) vaccines. These are the reactions of several experts on the matter.
Johnson & Johnson has just released preliminary data from its two-dose trial in a press release. It shows that the second dose increases the antibody response and also confirms the duration of protection among those who received one dose.