CORONAVIRUS/Taiwan health officials question COVID-19 antibody study

Taipei, Dec. 17 (CNA) The results of a study that estimates 0.05 percent of adults in Taiwan have COVID-19 antibodies was questioned by Taiwanese health officials on Wednesday, on the grounds that the people enrolled in the study might not accurately represent Taiwan's population.

The study under discussion was conducted by Taipei Veterans General Hospital. Although it was published in The Lancet Regional Health - Western Pacific journal on Oct. 10, it has only gained attention in recent days after local media reported on it.

In the study, blood samples that were left over from routine blood tests administered to 14,765 patients who visited the hospital from May 25-30 and July 6-8 were tested for antibodies of SARS-CoV-2, the virus that causes COVID-19.

The researchers wanted to test patients who visited the hospital at two different times to determine whether gatherings and activities held during the Dragon Boat Festival holiday (June 25-28) would result in COVID-19 infections, which would lead to a rise in the percentage of people who tested positive for antibodies.

The patients that were eventually enrolled in the study ranged in age from their 20s to their 90s and were comprised of 7,290 men and 7,475 women.

The samples were first tested using the Elecsys Anti-SARS-CoV-2 kit developed by Roche, a Swiss healthcare company. The 25 samples that were positive were then tested again with a test developed by Academia Sinica. Only samples with positive results from both tests were considered to be positive cases.

Of the total, 11 were concluded to be positive -- seven men and four women. Two were in their 90s, four were in their 60s, and there was one each in their 30s, 40s, 50s, 70s and 80s, the study said.

Seven came from the 9,777 patients who visited the hospital in May, while four were among the 4,988 patients tested in July.

As 78.2 percent of the patients enrolled in the study were over 50 years old, the researchers weighted the positive test results on age, estimating that 0.05 percent of Taiwanese adults over 20 years old, or 11,800, might have COVID-19 antibodies.

Given the data and their calculations, the researchers said that "a large proportion of Taiwanese people" might have contracted COVID-19, but were asymptomatic, only had mild symptoms, or were not qualified to receive a COVID-19 test.

Compared to estimates in similar studies conducted in other countries, such as one in Los Angeles that estimated 4.65 percent of people in the county had COVID-19 antibodies, and one in Geneva that estimated the prevalence to be 4.8 percent to 10.9 percent, the researchers said that the 0.05 percent estimate they have for Taiwan was "significantly lower than that of most regions in the world."

In addition, there was no significant difference in the percentage of people who tested positive for antibodies in May and in July, the researchers added, which indicates disease prevention measures taken by Taiwan have been "appropriate and effective."

When asked about the results detailed in the paper on Wednesday, Central Epidemic Command Center (CECC) advisor Chang Shan-chwen (張上淳) said that the patients included in the study might not be representative of Taiwan's entire population.

Since the study does not include information about whether these people had traveled abroad, Chang said he was unsure whether one could use the test results of 14,765 patients in Taipei to infer the infection rate for Taiwan's entire adult population.

The accuracy and sensitivity of the tests used may also not be as high as the manufacturers claim, Chang said.

CECC spokesperson Chuang Jen-hsiang (莊人祥) also voiced a similar view on Wednesday, saying that as the study did not indicate whether it included those returning from overseas and previous confirmed cases of COVID-19, the 0.05 percent figure should be considered an inference and not conclusive.

However, Chuang did say that the fact that only 11 people tested positive for antibodies out of 14,765 was an affirmation that Taiwan has done a good job in disease prevention.