SINGAPORE, April 26 — A team of clinician-scientists from the National University Health System (NUHS) has found that oral hydroxychloroquine and povidone-iodine throat spray are effective in reducing the spread of Covid-19 in high-transmission settings such as dormitories, cruise ships and prisons.

Their findings, which were presented to the media on Friday (April 23), were based on a study of more than 3,000 migrant workers living in Tuas South Dormitory during the height of the Covid-19 outbreak in dormitories in May last year.

Hydroxychloroquine is a prescription drug used to treat malaria and arthritis while povidone-iodine throat sprays are over-the-counter medications that provide symptomatic relief of sore throat.

The study is the largest done so far internationally on Covid-19 preventive therapy involving these drugs. It was published in the International Journal of Infectious Diseases on April 14.

Why the study matters

Speaking during a brief to the media on Friday, the study’s lead author Associate Professor Raymond Seet said that besides the vaccine, only two methods so far have proven effective in reducing the transmission of the coronavirus — wearing masks and social distancing.

However, this is the first study to demonstrate the benefits of preventive therapy with either oral hydroxychloroquine and povidone-iodine throat spray in closed settings, both of which are easily available and safe for use.

"This can represent a viable preventive strategy for individuals living in a closed and high-exposure setting, especially in areas and countries where Covid-19 vaccination is not available or widespread,” he added.

How the study was done

As part of the study, 3,037 migrant workers from Tuas South Dormitory aged between 21 and 60, with a mean age of 33, were recruited to participate in a randomised clinical trial.

The dormitory was chosen for the trial as it was still in the early stages of the Covid-19 outbreak, said Assoc Prof Seet, who is a senior consultant at the National University Hospital (NUH).

Speaking during a brief to the media on Friday, the study’s lead author Associate Professor Raymond Seet said that besides the vaccine, only two methods so far have proven effective in reducing the transmission of the coronavirus — wearing masks and social distancing.

However, this is the first study to demonstrate the benefits of preventive therapy with either oral hydroxychloroquine and povidone-iodine throat spray in closed settings, both of which are easily available and safe for use.

"This can represent a viable preventive strategy for individuals living in a closed and high-exposure setting, especially in areas and countries where Covid-19 vaccination is not available or widespread,” he added.

How the study was done

As part of the study, 3,037 migrant workers from Tuas South Dormitory aged between 21 and 60, with a mean age of 33, were recruited to participate in a randomised clinical trial.

The dormitory was chosen for the trial as it was still in the early stages of the Covid-19 outbreak, said Assoc Prof Seet, who is a senior consultant at the National University Hospital (NUH).

Key findings

By the end of six weeks, 1,681, or a little over half, of the participants were diagnosed with Covid-19.

The frequency of infection was also significantly lower in participants who used hydroxychloroquine or the throat spray, compared to Vitamin C.

The following are the infection rates for trialled medications: