Covid-19 antibodies in much of the population may not mean immunity

Preliminary results from a new nationwide seroprevalence study conducted by the Ministry of Health and Population show that 68.6% of the country’s population has already developed antibodies against Covid-19.

The latest findings of the study, the detailed report of which has not yet been released, indicate that SARS-CoV-2 has spread rampantly in communities and that measures taken to break the chain of transmission are being taken. inadequate and ineffective because more than two-thirds of the country’s population had already been infected before August 14.

Conducting such a large-scale survey of the general population provides public health agencies with a picture of the spread of infection in communities, especially during a pandemic that killed more than 10,700 people.

But on Sunday, a health ministry statement outlining preliminary results for antibodies and vaccine efficacy left room for misinterpretation, according to public health experts who say it would be dangerous to draw a hasty conclusion.

“We don’t know the percentage of antibodies… or if it is effective against the Delta variant of the virus currently circulating in communities,” Dr Dipesh Tamrakar, assistant professor at Kathmandu University, who served under the Community Department of medicine at Dhulikhel Hospital, told the Post.

In its statement on Sunday, the health ministry also said that similar levels of antibodies were found in people residing in the seven provinces, the three geographic areas – mountain, hills and Tarai, villages and towns, all sexes. , professions and groups.

Health ministry officials say the recent drop in new cases could be a reason two-thirds of the population are already infected with the virus and the risk of a massive explosion of new infections remains low.

Doctors, however, say it is impossible to develop a similar level of antibodies in people residing in the country’s seven provinces and in all three geographies, cities and towns and people of all ages.

“The development of similar levels of antibodies in all age groups has not happened anywhere in the world,” Tamrakar said. “Studies show it (antibody level development) varies with age, and this is a proven fact.

Some countries, including the United States, have decided to give a third dose in wakeup call to those whose immunity is compromised.

“We also don’t know whether or not the antibodies work against the new variant of the virus,” infectious disease and intensive care expert Dr Prabhat Adhikari told The Post. “For this a neutralization test is necessary, which we have not yet done.”

A neutralizing antibody is an antibody that is responsible for the defense of cells against the pathogen, which are organisms that cause disease. They are produced naturally by the body as part of its immune response, and their production is caused by both infection and vaccination against infections.

According to World Health Organization, available scientific data suggests that in most people, immune responses remain robust and protective against reinfection for at least six to eight months after infection (the longest follow-up with strong scientific evidence is currently around eight months).

People with a mild or asymptomatic infection tend to have lower antibody levels than those with severe illness. Some studies have suggested that the decrease in antibody levels occurs within months of infection in some individuals.

After the ministry’s statement on the seroprevalence study, some were quick to say that the country was on the verge of achieving herd immunity, a situation in which a large part of a community (the herd) becomes immune to one. disease, which makes it unlikely that the disease will spread from person to person.

Experts disagree.

“We are far from reaching a level of herd immunity, because a large number of the population has not yet been fully vaccinated,” said Dr Sher Bahadur Pun, virologist and head of the clinical research unit at Sukraraj Tropical and Infectious Diseases Hospital. the post office.

According to the ministry’s statement, doctors say 10% of the fully vaccinated population and 20% of those who took the first dose do not have antibodies. According to them, this means there is a risk of getting infected – seriously – and even of dying.

Although vaccination is the best way to protect against infection with SARS-CoV-2, some studies show that vaccines are less effective against the Delta variant, and discussions are underway to administer recalls.

The health ministry said the Delta variant of the virus is responsible for the ongoing infection across the country. Whole-genome studies in the past have also shown that the highly infectious Delta variant of the virus is circulating across the country.

“The study shows that people from the three geographies and the seven provinces have similar antibody levels,” Dr Samir Kumar Adhikari, joint spokesperson for the Ministry of Health, told the Post. “The study says a large number of people have antibodies, which may mean we may not see a full-scale epidemic immediately.”

Adhikari, however, concedes that the immunity developed by natural infections wanes after a certain period of time and that public health measures are still relevant.

So far, 5,317,483 people have taken their first dose of vaccine (17.7%) and 4,396,402 (14.65%) have been fully immunized.

“As the coronavirus continues to mutate, the immunity developed from one variant may not protect an individual from another lethal variant,” Pun said. “The risk has not diminished at all. The authorities concerned should always focus on preventive measures.

World Health Organization chief scientist Dr Soumya Swaminathan recently said that Covid-19 in India could enter some sort of endemic stage, where there is a low or moderate level of transmission.

Doctors say the situation will be different in Nepal if the virus becomes endemic in India.

As of Monday, 1,902 people tested positive for 11,892 polymerase chain reaction tests, and an additional 393 people tested positive for 4,341 antigen tests.

The positivity rate is around 16%.

Doctors say the drop in testing could be the reason for the decrease in the number of new cases. Currently, thousands of healthy people traveling abroad are tested every day. The Department of Health, in its daily report, also includes the test results of people looking for tests to obtain “negative reports” required to travel abroad for study or work, thus creating confusion over the actual Covid-19 situation.

“The infection rate has remained almost constant for months and the positivity rate has hovered around 15%,” Pun said. “We don’t know the exact extent of the spread, but Covid-19 could also become endemic in our country. “