More than 30 million Mexicans – about a quarter of the population – have been infected with the coronavirus, a serological testing survey suggests.

The National Institute of Public Health (INSP) collected 7,098 blood samples from adults, teenagers and children between August and November and found that 24.8%  had developed antibodies against the coronavirus.

If the percentage is extrapolated across the entire population of Mexico, approximately 31 million people have been infected with the virus, said INSP director Juan Rivera.

That’s about 24 times higher than the current official confirmed case tally, which stands at just under 1.3 million.

“It shows a high speed of spread,” Rivera said.

Just over 26% of males and 23.6% of females who provided blood samples had developed coronavirus antibodies. A quarter of people aged 20 to 59 had antibodies while among those aged 60 and over only 18% appeared to have had the virus.

“It gives the impression that people over 60 took more care, stayed at home more and followed all the [health] measures,” Rivera said.

Referring to the likelihood that one-quarter of Mexicans have already had the virus, the INSP chief said that means that “75% of Mexicans [still] don’t have immunity against Covid” and therefore the population is still a long way from achieving herd immunity.

“It’s a very high percentage, almost 100 million people. … We mustn’t be careless, we mustn’t drop our guard. … The vast majority of us are [still] vulnerable to infection,” he said, acknowledging also that there is a possibility of reinfection.

It is likely that a lot of people who have had the coronavirus weren’t aware that they were infected.

The INSP classified 70% of people who developed antibodies against the coronavirus as asymptomatic. Only 20% of people with coronavirus antibodies experienced the telltale symptoms of Covid-19 while the other 10% only had one mild symptom.

“Almost 80% without symptoms. What does this mean? Maybe a lot of us are asymptomatic and therefore we could be transmitting the disease without realizing it,” Rivera said. “That’s why it’s important to take all the precautions.”

The coronavirus pandemic has hit Mexico harder than most other countries. As of Wednesday, its accumulated case tally of 1.27 million was the 13th highest in the world while the official Covid-19 death toll of 115,769 was the fourth highest after the United States, Brazil and India.

Source: El Economista (sp), El Financiero (sp)