Covid, Omicron BA5 bypasses immunity but symptoms are mild – breaking latest news

1 What is Omicron BA5?

The virologist Giorgio Pal, president of the Italian drug agency Aifa, answers. BA5 is a sub-variant of the Omicron virus, which is prevalent in much of the world. Like previous BA1-2-3-4 lineages, variant of concern has been declared (variant of concern) by the European Infectious Disease Control Agency, ECDC, based on the rapid spread and ability to circumvent the defense of antibodies (immuno-evasion) and in causing serious illness.

Omicron BA5 has a contagious index very close to that of measles which is the most transmissible virus: an infected individual can infect another 15-18., A characteristic mainly linked to the ability to evade the immune response. Data from the college of health show that 7% of Italians who contracted the BA1 sub-variant when it was prevalent can be infected a second time. There is no evidence of a greater severity of the disease.

From South Africa, where it originated in February 2022, and not from Portugal, the European country where it initially spread, without affecting the rate of hospital admissions. Everything suggests that cases will increase in the rest of Europe and that Omicron BA5 will become predominant over the other sub-variants without stressing health systems. The incidence of infections is also increasing in Italy: we went from 207 cases per 100 thousand inhabitants at the end of May to 222 between 3-9 June. Intensive care and medical departments are not growing. (see also Quintupled cases in Milan today).

The South African population consists of many patients with compromised immune systems from other infections (tuberculosis, AIDS). Viruses such as Sars-CoV-2 have a greater chance of persisting in a chronic form in an organism that cannot reject them and consequently of undergoing mutations.

5 Why does it bypass immunity?

Thanks to two additional mutations compared to the Delta variant, located on the S protein, responsible for binding the virus to the receptor of human cells. These changes partly give it the ability to evade the antibody response (which allow us to prevent infection) but not cell-mediated immunity (which has the function of eliminating the virus from tissues and making us heal earlier). .

6 Are vaccines effective?

Although the current vaccines were all designed on the original Wuhan strain that circulated two and a half years ago, they induce 90% protection against severe forms (if you have been vaccinated with a full course, two doses plus booster). This is why it is important to do the third and fourth dose (for the frail, elderly over 80, immunosuppressed), guests of nursing homes for the elderly). In September-October we count on the availability of new vaccines built on the Omicron variant. Pharmaceutical companies Pfizer and Moderna are well advanced in the authorization process.

Forms of mild disease. Sore throat, runny nose, cough, fever. Like the other sub-variants Omicron BA5 mainly affects the upper respiratory tract and is characterized by three mutations that make it less infectious for the lungs.

A so diffusive and not very virulent virus capable of producing natural immunization on a large part of the population in addition to the artificial one produced by the complete vaccination course (third and fourth booster dose). This hybrid immune system is very protective against the disease and is able to stem the spread of the pandemic. The virus will persist but will occur seasonally. We will find preparations with updated vaccines (such as against the flu) and new antivirals.