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Coronavirus: Delta variants and vaccines

Delta variants of the coronavirus have now spread to about 100 countries. According to the World Health Organization, this variant will apply worldwide as a significant variant within two months. We formerly knew the Delta variants as the Indian variant or B.1.618.2. The first appearance of this variant was in India. Later it spread rapidly to the United Kingdom and Nepal. This delta variant was the primary cause of the terrible second wave of the Kovid epidemic in India. We have also seen the violence of the Delta variant in Nepal.

Delta variant and vaccines

The third wave of epidemics has started in Bangladesh on June 1. Eighty percent of the transmission in this wave is with the highly contagious delta variant. The onset of the third wave in the country started in the north-western districts bordering India. By the end of June, it has spread across the country.

There are new records of infections and deaths every day. On July 5, 174 people died, and about 10,000 were infected in one day across the country. This is the highest number of deaths and daily attacks in Bangladesh. So it is easy to assume that the country is heading for an enormous wave. The government, however, has imposed a strict nationwide lockdown from July 1 to prevent an epidemic.

Now the question is, how did the Delta variant take such a deadly form? Are the vaccines currently available effective against the Delta variant?

Origin of Delta variant

Although the Delta variant originated in India, it has been studied extensively in the United Kingdom. In the UK, 99 percent of infections are now with these Indian Delta variants. They identified the Delta variant in the UK in April this year in the town of Bolton. It surpassed the Kent or UK variant (B.1.1.6) within two months to become the main variant and spread across the country. The third wave is now underway in the UK with the Delta variant.

The Delta variant (B.1.617.2) is one of the three subtypes of the B1.617 known as the Indian ‘double mutant’. We identified it in India last December. Two significant mutations have occurred in the spike protein of the Delta variant. One is in the receptor-binding domain (L452R), and the other is at the furin cleavage site (P617R). These two components of the spike protein play an important role in transmitting and spreading the virus. Because of this simultaneous dual mutation, the Delta variant can transmit 40 to 60 percent faster than the UK or Alpha variant (B.1.1.6). This mutation has made the B1.618.2 variant a ‘best fit’ virus to survive in humans.

11 different mutations in the Delta variant

We have seen before the L452R mutation in the Delta variant in the California variant of the United States. A study in the Cell Journal, published April 20, 2021, found that L452R mutations increased the cell’s ability to infect the mutated virus. The risk of transmitting the virus to infected individuals was much higher than in infected individuals. This means that this mutation turns a new variant into an infectious virus. The study also showed that neutralizing antibodies could not neutralize this variant of the virus so efficiently. This means that the mutated virus is more likely to be vaccinated. Besides these two mutations, the Delta variant has 11 different mutations.

How the vaccine works on the Delta variant

Public Health England surveyed from 5 April to 16 May this year to see how the Oxford-AstraZeneca and Pfizer vaccines work on the Delta variant. They surveyed 11,821 people in the UK variant and 1,054 people in the Delta variant. A review of the results shows that a single dose of the Oxford or Pfizer vaccine protects against symptomatic covid with the Delta variant at only 33 percent and 51 percent against the UK variant.

Two doses of the Oxford-AstraZeneca vaccine increase the effectiveness of the Delta variant by 60 percent and the UK variant by 6 percent. Similarly, the two-dose efficacy of the Pfizer vaccine is 61 percent against the Delta variant and 6 percent against the UK variant. This means that two doses of the vaccine are essential to prevent infection of the Delta variant.

Can the vaccine save lives from the Delta variant?

Another critical issue is whether the vaccine can save lives from the Delta variant. To see this, Public Health England recently conducted another survey of 14,000 patients with the Delta variant. They published the results of the study in a pre-print on their website on June 14. It found that two doses of the Oxford vaccine saved 92 percent of severe covid and hospitalizations. With a single amount, the number stands at 61 percent. We have seen similar results with the Pfizer vaccine. Ninety-six percent of those who received the two-dose Pfizer vaccine were saved from being hospitalized with severe colic. And of those who took a dose, 94 percent were free of the deadly covid.

Another critical point here is that out of the 14,000 delta variant patients admitted to the hospital, none died in Kovid. The Oxford or Pfizer vaccine has prevented death from covid. However, according to Public Health England, there may be some slight changes in future mortality statistics. This ‘real-life evidence’ confirms that the two doses of the Oxford-AstraZeneca and Pfizer vaccines provide an average of 94 percent protection against the deadly or severe covid caused by the Delta variants. And those who have taken a dose of the vaccine will be 75 percent protected from the fatal covid.

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The average mortality rate in the third wave is 1.6

At present, it infected an average of one in four people in Bangladesh with the coronavirus. The virus’s current reproduction rate (R-Knot) is 1.4, and the doubling time is 14 days. This means that the number of covid patients is doubling every two weeks. Over one thousand people are dying in Kovid every 15 days. About 60 thousand are being infected. The average death rate in the third wave is 1.6. During the second wave, one thousand people died every 30 days (March 10 to April 9), and about 120,000 people were affected in 30 days. The death rate in the second wave was zero point 83. There was no Delta variant in the country during the second wave.

Thus, the mortality rate of the third wave is twice the mortality rate of the second wave. So the question is, is the Delta variant responsible for this increase in mortality? The answer is hard to confirm. It could be the Delta variant is deadly. But there may be another reason. However, the onset of the third wave is in the border districts, where the daily transmission rate is skyrocketing and hospital treatment is inadequate. And that’s probably why the death rate has doubled. If this is true, then the government will have to make some changes in the medical management of Kovid. We should increase medical capacity in district hospitals outside the capital city two to three times. In addition, it will not be possible to prevent upward mortality.

The only effective and long-term approach is vaccine

However, the only effective and long-term solution to the epidemic is the vaccine. To overcome the epidemic and return to everyday life, at least 80 percent of the people in the country will have to be brought under the epidemic. So far, they have given only 4 percent of Bangladesh a single dose of the vaccine.

The covid-19 epidemic is not leaving the world so soon. This epidemic will continue next year, and one wave after another will come a few months later. Lockdown may reduce temporary infections, but it is not a long-term measure. Two-thirds of the country’s population needs to be vaccinated as soon as possible to recover from the epidemic and return to everyday life. It is not possible to achieve the target this year because of the shortage of vaccines. So the elderly and high-risk people should be vaccinated on a priority basis. This will save many lives in this epidemic. Whatever the coronavirus variant, the vaccine is less effective than all other variants and holds almost 100 percent energy.

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