Fudged data shows high vax coverage in Tamil Nadu; experts cry foul

CHENNAI: Two gross statistical errors made by the directorate of public health have falsely projected 62% of Tamil Nadu’s population as being relatively safe against Covid-19 infection. Public health experts now fear this claim may not just underestimate risks but also have a drastic impact on the policies, plans and funding the department receives amidst the anticipated third wave.
Analysis by TOI showed that the DPH fudged vaccination coverage figures in its daily report to the state government to hype coverage to 30%, though it is only half that in reality.
For instance, on July 20, the vaccination coverage report said that of the eligible 6.06 crore adults in the state, 1.49 crore people have taken the first dose and 34.22 lakh have taken the second dose. This means nearly 25% of the population has taken the first dose and 6% has taken the second dose.
So, how does the directorate claim its 30%?
A senior official in the public health department said they simply added the number of people who took the first dose and the number of people who took both doses to show the number of doses that have been completed. Epidemiologists point out that in that case, officials should have divided the tally with the dosage target, which is twice the population because everyone gets two doses of the vaccine.
The target dosage, in that case, would have been 16%, just half of what the government’s claim. This is because less than 2 crore of the 12-crore doses were administered until July 20.
“This is needless misinterpretation of data, which can cause serious problems when the data is used to plan health policies, including unlocking strategies and preventive steps against the anticipated third wave,” said public health expert R Sunderraman, former director of the National Health Systems Resource Centre. “Everyone knows there is a vaccine shortage. What is wrong in saying the exact number?” he said.
Data reporting gets worse when the DPH uses an unscientific method of adding serosurvey results to spruce up the number of people with antibodies. Two doses of the vaccine help people develop artificially-induced antibodies that give them protection against the virus. But people who are naturally infected also develop these antibodies. The state has done three serosurveys to measure antibodies in people. The first survey, done in 2020 before the vaccine launch, showed 32% of people had antibodies.
Senior microbiologists like Dr Gagandeep Kang from Vellore Institute of Medical Sciences had earlier told TOI that seropositivity rates and vaccination rates cannot be added, as some seropositive individuals would have been vaccinated later. “Even with high levels of seropositivity and vaccination, we still have a large population that is unprotected. But that will, hopefully, decrease with increased vaccine coverage over time,” she said.
The state has added this number to the number of people vaccinated to show that 62% of the people have developed antibodies. The percentage of people with antibodies dropped to 23% in the second phase done in April. The comprehensive results of the third phase, which is expected to be higher than the first two phases, is still not available.