Vaccines still protect against new Covid-19 variants: WHO chief Ghebreyesus

 WHO experts emphasised that vaccines are still highly effective against Covid-19, even against the new variants of the disease emerging in South Africa and the US

Experts from the World Health Organization (WHO) emphasised on Wednesday that vaccines are still highly effective against Covid-19, even new variants of the disease emerging in South Africa and the US. WHO data shows that global cases of Covid-19 are continually declining, with reported weekly deaths at their lowest level since March 2020. However, the Organization’s Director-General Tedros Adhanom Ghebreyesus cautioned at a press briefing on Wednesday that these trends don’t tell the full story, Xinhua news agency reported.

“Driven by Omicron sub-variants, we are seeing an increase in reported cases in the Americas and Africa. The South African scientists who identified Omicron late last year have now reported two more Omicron sub-variants, BA.4 and BA.5, as the reason for a spike in cases in South Africa,” he said. “It’s too soon to know whether these new sub-variants can cause more severe disease than other Omicron sub-variants, but early data suggests vaccination remains protective against severe disease and death,” he added….

Omicron may not be the final variant, but it may be the last of concern

 The disease might very likely be mild as some past exposure creates immunity that reduces the likelihood of hospitalisation and death

It is controversial whether viruses are alive, but – like all living things – they do evolve. This fact has become abundantly clear during the pandemic, as new variants of concern have emerged every few months. Some of these variants have been better at spreading from person to person, eventually becoming dominant as they out-compete slower versions of SARS-CoV-2, the virus that causes COVID-19. This improved spreading ability has been ascribed to mutations in the spike protein – the mushroom-shaped projections on the surface of the virus – that allow it to bind more strongly to ACE2 receptors. ACE2 are receptors on the surface of our cells, such as those that line our airways, that the virus attaches to in order to gain entry and start replicating.

These mutations allowed the alpha variant, and then the delta variant, to become globally dominant. And scientists expect the same thing to happen with omicron. The virus cannot, however, improve indefinitely. The laws of biochemistry mean that the virus will eventually evolve a spike protein that binds to ACE2 as strongly as possible. By that point, the ability of SARS-CoV-2 to spread between people will not be limited by how well the virus can stick to the outside of cells. Other factors will limit virus spread, such as how fast the genome can replicate, how quickly the virus can enter the cell via the protein TMPRSS2, and how much virus an infected human can shed. In principle, all of these should eventually evolve to peak performance.