India’s claim that there have been very few post-vaccination infections is based on incomplete data

The central government has claimed that only two to four persons in every 10,000 vaccinated with either of the two Covid-19 vaccines being used in India are seeing breakthrough infections, when a vaccinated person gets infected.

However, this is based on incomplete data – for nearly three months after vaccination began, the government’s Covid-19 test form, used by both government and private laboratories, did not check if those being tested had been vaccinated. Cases of post-vaccination infection would therefore not have been detected and recorded, our ground investigation and review of documents shows.

The methodology used by the government is questionable, experts on virology told us.

In clinical trials, both the two-dose Covid-19 vaccines Covishield and Covaxin being used have been shown to lower the risk of death, severe disease and mild infections in vaccinated individuals, even after only the first dose. Published Phase III trial results for Covishield showed a 70% vaccine efficacy in preventing symptomatic Covid-19 and 100% efficacy in preventing severe disease and death. Phase III trial results for Covaxin have not yet been published, but the manufacturer claims a slightly higher vaccine efficacy of 78%.

Vaccine efficacy is the degree to which a vaccine prevents infection in vaccinated groups, in closed, controlled clinical trials. Vaccine effectiveness, on the other hand, refers to how well a vaccine performs once it is approved for use and out in the real world.

Government’s claim

In appearing to demonstrate high vaccine effectiveness for both Covaxin and Covishield, however, the central government has used problematic data, we found. The numbers of persons receiving Covaxin and Covishield doses, and the number of breakthrough infections, ie Covid-19 cases reported by vaccinated persons after the first and second dose were shared by Union health secretary Rajesh Bhushan at a press conference on April 21.

“As everyone knows, there are two vaccines currently in use in our country,” said Balram Bhargava, director general of the Indian Council of Medical Research. “They prevent severe disease and death and definitely reduce infections. After vaccination, if we get infection, it is known as breakthrough infection.”

Only 0.02% to 0.04% – or two to four per 10,000 – of vaccinated persons saw breakthrough infections after Covid-19 vaccination, which is a very small number, but even these few infections could be explained partly by the higher exposure of the infected persons compared to the general population, and to the ongoing second surge in India, added Bhargava.

He ascribed “this small number” to healthcare and frontline workers who were the first to be vaccinated. “They are prone to more occupational exposure... But this is a very, very small number and not at all worrisome, and vaccination should continue,” said Bhargava, “The second point is that the current highly transmissible second wave may also contribute a little bit, or miniscule, to this percentage. Otherwise, this could have been even 0%.”

At the same press conference, Vinod Paul, member (health), NITI Aayog and head of India’s Covid-19 task force, said he wanted to make the point that these incidents of breakthrough infections are very low and, though research is going on, even if these occur there will be no severe Covid-19 disease, as per the data with the government till date. The government was systematically collecting data on breakthrough infections, he added.

Details not sought

Until recently, however, ICMR’s Specimen Referral Form, which laboratories are required to fill up when conducting a Covid-19 test, did not ask for information on whether the person being tested had been vaccinated against Covid-19 or not.

On April 7 – nearly three months after India began its vaccination programme – the form was amended to include questions on whether the person being tested had received the Covid-19 vaccine. If so, then which one. And the dates on which the first and/or second doses had been received. This means that tests conducted for 81 days prior to April 7 did not contain this information, a senior official at the ICMR admitted, asking not to be named.

Even now, the changed ICMR form has not fully made it to the ground, we found. The government’s own National Centre for Disease Control’s checklist of forms (accessible on this page) carries the old version of the ICMR Specimen Referral Form, without fields for vaccination information. The websites of large diagnostic test providers including Max Labs, SRL Diagnostics and Apollo Labs all still have the old ICMR form until today. This means that many people who are testing positive for Covid-19 after getting vaccinated are still not being reflected in ICMR’s data on breakthrough infections.

Siddharth Chakravarty, a 38-year-old researcher with an NGO, got his first dose of the Covishield vaccine at a government primary health centre in Bengaluru on April 2. After experiencing mild symptoms, Chakravarty got himself tested for Covid-19 at a private lab in Delhi on April 19 and was positive. He was not required to give any details about prior vaccination, he said. (IndiaSpend reviewed his documents.)

B Sumana (name changed on request to protect identity), 69, got her first dose of Covishield on April 3 in Chennai. On April 17, she experienced mild Covid-19 symptoms and got herself tested at a private lab.

Again, no details on prior vaccination were sought. She then received a text message confirming receipt of her sample with a link to the ICMR’s Covid-19 Sample Collection Management System portal, from which she could download her Sample Referral Form.

In the personal details section was the question: received the Covid-19 vaccine? The form had already been filled out with the answer “no”, even though she had never been asked the question, and had actually received one dose. She tested Covid-19 positive. (IndiaSpend has reviewed all her documents.)

At least two deaths from Covid-19 of vaccinated people have been reported in mainstream media. A father-son duo of doctors in Kalyan, Maharashtra who died on April 17, had both received the first dose of a vaccine. Relatives said they had tested positive for and died from Covid-19.

Questionable methodology

IndiaSpend sought a response from ICMR early on April 22, asking what methodology was used to collate numbers of breakthrough infections, and seeking clarifications about facts uncovered by our ground reporting. The article will be updated should they respond.

“There is a World Health Organization guidance for conducting vaccine effectiveness trials in low and middle-income countries,” said Gagandeep Kang, one of India’s leading virologists. “This is absolutely not the way to measure it. There are ways to do even small trials for vaccine effectiveness, but this is not it.”

“You can not first find people who test positive and go back to see if they were vaccinated,” she said. “You need to start with the vaccinated population and see whether they get infected. In addition to the problems on the ground that you are pointing out, there will also be [vaccinated] people who test positive later.”

“There will be [vaccinated] people who feel sick, but never get tested,” she said.

This article first appeared on IndiaSpend, a data-driven and public-interest journalism non-profit.