One of the characteristics of viruses is their extraordinary ability to reproduce and, in the process, copies with changes tend to appear. So it was no surprise when the one that causes covid-19 (called SARS-CoV-2) started to generate variants as it spread around the world.
Today, there are about 30,000 acquaintances, and they have been closely monitored since the coronavirus appeared in the city of Wuhan, China. Among all strains, three have the potential to change the course of the pandemic and, for this reason, are called variants of concern (variants of concern, or VOC). The more the virus replicates and spreads, the greater the chances of variants appearing.
There are more than 30,000 variants of SARS-CoV-2 known, but few have the potential to be more deadly.Source: GISAID / Rob Lanfear / Disclosure
The speed with which the virus replicates does not excel in its care in reproducing its genetic code without errors, which ends up generating mutations. Many are lost by the death of the virus; others are harmless, but some are viable and make the virus more resistant, the disease more contagious, its effect more deadly.
The variations spread and accumulate, given the speed with which the virus enters cells, reproduces frantically and takes over the body, jumping from one individual to another. This is the great challenge in producing a vaccine.
The first variant that raised concern among researchers came in the UK. Just before Christmas 2020, samples taken from two patients showed that the coronavirus had changed, a lot. 23 mutations were recorded: 13 changed the protein sequences of the virus and eight, in the spike protein – the tips of the virus crown and responsible for making it attach to the ACE2 receptor on the membrane and thus, manage to infect the cell.
The proportion of the variant among covid-19 cases began to skyrocket in the weeks that followed, leading researchers to realize that the virus had incorporated a mutation that made it able to spread more easily from person to person. One of the mutations in this variant, N501Y, changes the amino acid at position 501 of the spike protein sequence.
Earlier this year, the British government again decreed a lockdown to try to halt the advancement of the new coronavirus strain.Source: Reuters / Reproduction
This exchange took place exactly in the region where the virus binds to the ACE2 receptor; in mice, the change showed that the virus became more efficient at binding to the cell, making the disease more infectious and virulent. Another mutation, called P681H, increased the virus’s ability to fuse with the membrane and dump its contents into the cell.
These and other mutations have increased the transmission capacity of the virus by up to 56%, contaminating the population of more than 60 countries – according to the American Center for Disease Control and Prevention (CDC), it should be the country’s predominant strain by March. In Brazil, the first two cases were detected in São Paulo.
Even though in relative numbers there is no evidence that B.1.1.7 increases the severity of the disease or causes more deaths, the higher rate of contagion (and the overcrowding of health facilities) increased the total number of more serious cases and deaths , in absolute numbers.
On January 21, the New and Emerging Respiratory Virus Threats Advisory Group (New and Emerging Respiratory Virus Threat Advisory Group, or NERVTAG) said that “there is a realistic possibility that infection with VOC B.1.1.7 is associated with an increased risk of death ”.
The concern then turned to vaccines that are being used to fight the pandemic and its effectiveness against the new variant. Pfizer / BioNTech and Moderna, the laboratories that produce the so-called gene vaccines (based on messenger RNA), have already declared that the immunizers remain effective against the new strain.
Just before the world became aware of B.1.1.7 sweeping the UK, health officials in South Africa announced that a variant was prevalent among the cases of the disease reported in the Eastern Cape, Western Cape and KwaZulu-Natal provinces: to 501Y.V2, named for having one of the mutations found in B.1.1.7 – the one that increases the efficiency of the virus to bind to the cell membrane, increasing the virulence of covid-19.
A nurse at Lancet Nectare Hospital collects material for a coronavirus test in Johannesburg in December 2020.Source: AFP / Luca Sola / Reproduction
Twenty-one mutations were detected in this variant, including the one mentioned above. Two others, however, have left experts concerned about the immune response. The mutations (both in the spike proteins) are known as K417N and E484K. If the first makes the action of antibodies less effective, the second reduces the immune response by up to ten times. However, mRNA-based vaccines still protect those receiving the immunizer, even if there is a drop in efficiency.
The more viruses spread, the more likely it is to mutate and create variants – time and the number of hosts count in your favor. The third variant appeared in Manaus (AM), after the city was devastated by the covid-19 until mid-2020 – in October, 75% of the population had already been infected. Two months later, the cases rose again, but this time, with more speed: the SARS-Cov-2 had evolved to the P.1 variant.
It gathers ten mutations in its spikes, including the aforementioned N501Y, E484K and K417T, which may indicate that the disease is more easily transmitted, more virulent and causes less immune response – if it is more deadly, it is still unknown but the consequences of its evolution are also measured by the collapse of the state hospital network.
A month ago, the variant accounted for 42% of the SARS-CoV-2 samples sequenced in Manaus; now, it is in 91.4% of the samples collected this month in the state, according to the Leônidas & Maria Deane Institute (ILMD / Fiocruz Amazônia) and Amazonas Health Surveillance Foundation.
Patients occupying clinical beds in hospitals in Manaus began to be transferred to other states in mid-January.Source: Ministry of Health / Disclosure
P.1 is already in seven countries, and the fear of health authorities now is that it will spread throughout Brazil by sending patients to other states, due to the lack of oxygen in hospitals in Manaus. There is still no data on the effectiveness of vaccines currently distributed in Brazil in combating this variant of SARS-CoV-2.