Researchers are trying to understand several variants of coronaviruses that are now circulating in India, where the wild second wave of COVID-19 destroyed the nation and left the authorities unknowingly. Almost 400,000 new infections were reported in the country on May 9, for a total of more than 22 million (see “COVID-19 Surgical Cases”).
There is growing evidence that one variant first identified in India could be more transmissible and slightly better at evading immunity than existing variants. Animal models also suggest that it could cause more serious diseases. Researchers want to know if this variant and others can be the driving force behind the second wave and what dangers they pose globally.
In just a few weeks, variant B.1.617 became the dominant strain in India and spread to about 40 countries, including the United Kingdom, Fiji and Singapore.
A growing problem
Two weeks ago, it looked as if several variants were behind a series of surges in India. Genomic data suggest that B.1.1.7, first identified in the United Kingdom, was dominant in Delhi and the state of Punjab, and a new variant called B.1.618 was present in West Bengal. B.1.617 was dominant in Maharashtra.
But since B.1.617 has overtaken B.1.618 in West Bengal, it has become a leading variant in many states and is growing rapidly in Delhi. “In some states, the increase may be associated with 617,” Sujeet Singh, director of the New Delhi-based National Center for Disease Control, told reporters on May 5.
Some say this could indicate that the variant is highly portable. “Its prevalence has increased compared to other variants in much of India, suggesting that it is in better shape than these variants,” said Shahid Jameel, a virologist at Ashoka University in Sonipat, who chairs the SARS-CoV 2 genome sequencing consortia (INSACOG).
Ravindra Gupta, a virologist at the University of Cambridge in the UK, agrees that it is “highly likely to be more transmissible”.
On Monday, the World Health Organization (WHO) identified B.1.617 as a “variant of concern.” Variants are classified in this way if there is evidence that they spread faster, cause more serious disease, or better avoid previously acquired immunity than circulating versions of the virus. On 7 May, the UK government has already declared subtype B.1.617.2 as a variant of interest in the UK. It has been shown that the recorded B.1.617.2 infections in the country increased from 202 to 520 in a single week.
Several other variants of concern have had a significant impact worldwide. These include B.1.351, which was identified in South Africa at the end of 2020; Studies suggesting that the University of Oxford – AstraZeneca strike is less effective against this option have led the nation to suspend implementation. Similarly, variant P.1, which is able to avoid some immunity, contributed to a significant second wave in Brazil earlier this year. And the highly transmissible strain B.1.1.7 appeared in the United Kingdom at the end of 2020 and led to an increase in cases there and elsewhere.
The data on B.1.1617 are still flowing, but the mosaic of finds suggests that it is ahead of the variants that are already circulating in India.
Indian researchers first detected B.1.617 in several samples in October. At the end of January, INSACOG strengthened surveillance in response to a growing number of variants, and scientists have noticed that B.1.617 in Maharashtra is growing. By mid-February, that was 60% of cases, says Priya Abraham, director of the National Virology Institute (NIV) in Pune. Since then, several sublines have appeared.
In a detailed genomic and structural analysis B.1.617 published as a preprint1 On May 3, NIV researchers identified eight mutations in the viral protein of the spike that gain entry into cells. Two of them look similar to mutations that allowed other transmissible variants to become more transmissible, and the third resembles a mutation that may have allowed P.1 to partially avoid immunity.
The work on genomics was backed up a few days later by pre-printing2 from a team in Germany that shows that B.1.617 is slightly better than the previous variant when entering human intestinal and lung cells in the laboratory.
It is not clear whether this “small” advantage could lead to greater distribution in the real world, says lead author Markus Hoffman, an infection biologist at the Leibniz Institute for Primate Research in Göttingen.
Small animal studies suggest that the variant could cause more serious disease. In the prepress on May 53a team led by virologist Pragya Yadav of NIV found that hamsters infected with B.1.617 had more lungs in their lungs than animals infected with other variants.
Potential causing disease
Gupta says this research shows that B.1.617 has an increased potential to cause disease. However, he warns that “it is difficult to extrapolate from hamsters to humans” and says that data on the severity of the disease in humans are needed.
Research4 from Gupta’s own laboratory suggests that the antibodies are slightly less effective against the variant than against the others. The team collected blood serum from nine people who received a single dose of Pfizer vaccine and tested them against a harmless carrier virus modified to contain the SARS-CoV-2 protein, with mutations from B.1.617. Serum from vaccinated individuals usually contains antibodies that can block or “neutralize” the virus and prevent cell infection.
Gupt’s team found that neutralizing antibodies generated by vaccinated individuals were about 80% less effective against some mutations in B.1.617, although it would not make vaccination ineffective, he says. The researchers also found that some healthcare professionals in Delhi who had been vaccinated with the Indian version of Oxford – AstraZeneca Covishield had been reinfected, with most cases being associated with B.1.617.
The German team tested similarly2 serum from 15 people who had previously been infected with SARS-CoV-2 and found that their antibodies neutralized B.1.617 about 50% less effectively than previously circulating strains. When they tested serum from participants who had two shots of Pfizer vaccine, they found that the antibodies were about 67% less effective against B.1.617.
Two other small studies, one from Yadav’s team5 testing of Covaxin vaccine manufactured by the Indian company Bharat Biotech in Hyderabad and An unpublished study at Covishield showed that the vaccines continued to work. However, Yadav observed small decreases in the effectiveness of the neutralizing antibodies generated by Covaxin.
Variant B.1.617 appears to have an advantage over previously circulating versions of the virus, especially in individuals whose immunity has been declining for some time after a previous infection or vaccination, says Hoffman.
Caution and caution
However, Gupta warns that all of these laboratory studies involve small groups and show a smaller decrease in antibody potency compared to what has been observed with other variants of interest.
Researchers also warn that serum experiments are not always a good guide to whether a variant can avoid vaccine immunity in the real world. Vaccines can cause the production of large amounts of antibodies, so the decrease in potency may not be significant. In addition, other parts of the immune system, such as T cells, may not be affected.
For example, variant B.1.351 has been associated with much steeper decreases in the efficacy of neutralizing antibodies, but human studies suggest that many vaccines remain highly effective against this variant, especially in the prevention of serious diseases.
For these reasons, vaccines are likely to remain effective against B.1.617 and reduce serious disease. “The vaccine still works,” says Yadav. “If you get vaccinated, you will be” protected and the severity will be less. “
“However, the increase in cases in India and the scenes witnessed there are of serious international concern,” Nick Loman, a microbial genomic and bioinformatics specialist at the University of Birmingham in the UK, told Science Media Center in London after the UK announced B. 1.617.2 variant of interest. “This variant will now be closely monitored.”