The Delta variant of COVID-19, identified for the first time in India, is increasingly worrying scientists around the world and makes some think that it could delay the end of the pandemic by several months, since it is more communicable.
In addition, the evidence found in patients in India and the United Kingdom suggests that the Delta variant can cause a more severe disease and increase the risk of hospitalization for COVID-19, as it can be linked to symptoms such as gangrene. This is what we know.
A more transmissible variant
British scientists indicated that the Delta variant of the coronavirus, first identified in India, is 60% more transmissible than the Alpha variant, which was previously dominant in the UK, a leading epidemiologist said on Wednesday.
The Alpha variant is much more transmissible than the original variant of the coronavirus that emerged in Wuhan, China.
“Last week we had evidence that the Delta variant had a 30-100% transmission advantage over the Alpha variant (…), and that has been confirmed, we think 60% is probably the best estimate. “Neil Ferguson of Imperial College London told reporters.
“Last week we had evidence that the Delta variant had a 30-100% transmission advantage over the Alpha variant (…), and that has been confirmed, we think 60% is probably the best estimate. “Neil Ferguson of Imperial College London told reporters.
In other research carried out by the SARS-CoV-2 Genome Sequencing Consortium of India (INSACOG) and the National Center for Disease Control (NCDC), to which the EFE agency had access on Monday, it was indicated that the Delta variant was able to achieve a high speed of propagation despite the levels of seroprevalence present among the population.
The preliminary study, which has yet to be reviewed, nevertheless clarifies that this mutation had no influence on the exponential rise in the mortality rate with up to 4,000 deaths per day, which could be associated with the poor health system, among other factors.
According to the study, the Delta variant has “a high transmissibility (…) that is up to 50% higher than B.1.1.7”, the Alpha variant, detected for the first time in the United Kingdom, due to a higher load viral and immune escape ability.
“Despite the fact that last April the Indian capital had experienced three waves of the virus, and the seropositivity was around 50%, Delhi was overwhelmed by the fourth wave,” underlines the report that tries to find the reasons why the virus managed to evade herd immunity levels.
The high transmission of the Delta variant was also seen in the northern state of Punjab where the Alpha variant, which had reached a prevalence of almost 100% in this region, was consistently replaced by the Delta variant.
Even so, the study ruled out a higher mortality associated with the Delta variant, compared to the Alpha, noting that the alarming number of deaths in India may be due to a combination of multiple factors, including the collapse of the health system, with a lack of ICU beds and medical oxygen.
A more severe variant?
There is some evidence in the UK and India that the Delta variant can cause more severe disease than the parent virus. According to doctors from the Asian country, they have linked the Delta variant with symptoms such as hearing problems, severe graphic disorders and blood clots that lead to gangrene.
Some patients develop small blood clots, so severe that they led the affected tissue to die and develop gangrene, Ganesh Manudhane, a cardiologist from Mumbai, in the region hardest hit by the second wave of COVID-19 in India, told Bloomberg. “I saw three to four cases throughout the past year, and now it’s one patient a week,” Manudhane said.
In England and Scotland, early evidence shows that the variant – which is now dominant in some northern regions of the UK – carries an increased risk of hospitalization.
But there are some scientists who ask for caution about attributing to this or other variants of the virus a greater lethality.
Adul Ghafur, an infection disease specialist at Apollo Hospital in Chennai, South India, told Bloomberg that more research will be needed to find out whether the new clinical manifestations of the disease are linked to the Delta variant or not. Although he indicated that he has seen more cases of COVID-19 patients with diarrhea now than at the beginning of the pandemic.
“There is selective pressure on a virus to become more transmissible, because a virus wants to replicate as much as possible. But there is not the same selective pressure on viruses to be more lethal and the virus is not interested in killing its host. The most successful virus is one that lives in its host indefinitely, “wrote the virology Kirsty Short, from the University of Queensland, in.
The Beta and Gamma variants – first detected in South Africa and Brazil, respectively – have shown little or no evidence of triggering unusual clinical signs in COVID-19 patients, according to a study conducted in the
Vaccines still work, but in two doses
Some data suggest that Delta has the ability to evade the immune system. This is assessed by looking at the amount of antibodies in vaccinated people and then seeing how well those antibodies neutralize the virus in the laboratory.
“In fact, there is a decrease in antibody protection with this variant. The key to note, however, is that a drop in antibodies in laboratory tests does not necessarily seriously hamper vaccines. Laboratory results need to be addressed. with caution, “said Short.
According to data from Public Health England, the first dose of the Pfizer and BioNTech and AstraZeneca vaccines provide only about 30% protection against delta, although this increases to at least 88% after the second dose of the Pfizer vaccine and 60 % after the second dose of AstraZeneca vaccine.
“After a single dose of Pfizer / BioNtech, 79% of the people had a detectable antibody response against the original strain, but this was 50% against the Alpha variant, 32% against Delta and 25% against to Beta, “according to the Francis Crick Institute in London, author of a study in conjunction with the British National Institute for Health Research (NIHR), published last week
In parallel, the study showed that after the two doses of the Pfizer vaccine, the level of protective antibodies was lower in the presence of Delta than in the other two variants, crowning previous research, such as one carried out by the Pasteur Institute of France.
However, these levels of protection still exceed the 50% effectiveness threshold established by the World Health Organization to consider a safe vaccine.
“The real risk is when you consider the general population, where many people are not vaccinated or only have one dose of the vaccine, combined with the increased transmissibility and severity of Delta disease,” Sam Fazeli, senior pharmacist analyst at Bloomberg and director of research for the Europe, Middle East and Africa region.
But there is a change in this variant that may even be hopeful about its relationship with vaccines.
“What is quite surprising about Delta is that it has lost the key mutation that had people worried about the Beta and Gamma variants (…). This is one of the mutations that contributed to the loss of response to some antibodies, including those produced by vaccines, ”Fazeli wrote.
With information from AFP, EFE and Reuters
