The discovery of the Omicron variant has led to the cancellation of flights to several African countries, while many countries are beginning to detect cases among travellers from countries such as South Africa, but also Nigeria and Egypt. Spain has just announced the first detected case of Omicron, which corresponds to a traveller who had visited South Africa. What measures should be taken to stop the spread of this variant? Is it even possible?

A new variant of the coronavirus causing COVID-19 has been identified in South Africa, with numerous mutations present in other variants, including Delta. Variant B.1.1.529, as it is now called, appears to be spreading rapidly in South Africa. Attached is the rapid reaction of three Spanish researchers with expertise in genomic surveillance.

The message that we must continue to protect ourselves with masks, distance, ventilation and hand washing has been repeated since the beginning of vaccination, but in the midst of the pandemic in Europe it is even more important. Several experts warn that the high vaccination coverage in Spain will mitigate the new wave but will not eliminate it: although vaccines prevent serious disease, they are not an insurmountable shield and must be complemented with behavioral measures.

European countries are implementing anti-covid strategies in the unvaccinated population. Austria will make vaccination mandatory after extending its confinement targeting the unvaccinated to the entire population. In Germany, the unimmunized have restricted access to restaurants and hotels, and must show a negative test on public transport. Slovakia has also imposed restrictions on those who have chosen not to be vaccinated. Sweden will introduce a covid passport at events of more than 100 people. What is the effect of these policies?

The United States has already approved the vaccination of children aged 5-11 years against covid-19. In Europe, the European Medicines Agency (EMA) will decide in the coming weeks on the use of the Comirnaty vaccine in this population. Here is what several Spanish paediatricians think about it.

A study has monitored T-lymphocyte responses to the SARS-CoV-2 spicule in 71 healthy donors who received two doses of Pfizer's vaccine. After up to six months' follow-up, the researchers found that specific memory cells were generated and maintained and persisted for at least six months.

A clinical trial in Brazil evaluated the effectiveness of a depression drug versus placebo in reducing the risk of hospitalisation for SARS-CoV-2 infection. Administration of 100 mg twice daily for ten days to high-risk outpatients with early diagnosis reduces the need for hospitalisation.

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.