S’pore Experts Rebuts US Study That Claims COVID-19 Reinfection is More Dangerous


Reinfected patients were twice as likely to die and three times more likely to be hospitalised… or maybe not.

Singapore’s own medical experts slam this study, citing issues in their data and that they were confusing association with causation.

Here’s what the study claimed, and what our experts said in response.

Study’s Main Claim

The study, done by the Washington University School of Medicine and the Veterans Affairs (VA) St Louis Health Care System, claimed that COVID-19 reinfection is more dangerous.

They concluded that patients with reinfections were twice as likely to die and three times more likely to be hospitalised than first-time infections.

Out of a total patient population of 5.8 million, the researchers looked at 41,000 VA patients who have been reinfected, and 444,000 VA patients who had first-time infections.

Didn’t Take Into Account Patients’ Medical History 

The study claimed that those who were reinfected were 3.5 times more likely to develop lung problems, and three times more at risk to suffer heart conditions.

Duke-NUS Medical School’s Professor Ooi Eng Eong rebutted this, pointing out that the study didn’t provide much information on the chronic diseases that the reinfected cases had.

Additionally, they didn’t look at patients with other respiratory infections. This means that they can’t prove the higher risk is specifically due to COVID-19, and that any viral infection might also have the same effect.

NUH’s Professor Paul Tambyah, who is also the president-elect of the International Society for Infectious Diseases, also pointed out that the reinfected and first-time infected groups were very different.

The data showed that the reinfected group of patients were three times more likely to be immunocompromised, and nine times more likely to be in long-term care.

It would not have been fair to compare these two groups, given their very different medical histories.

This isn’t even factoring in how the reinfected group was very small, at 41,000 patients out of 5.8 million in the entire database. With such a sample size, any interpretation would not have been able to make meaningful conclusions for the wider population outside of the VA.

Additionally, the VA patients tend to be older male patients who smoke or have serious health problems. Conclusions drawn from their data thus may not apply for the general population.

SG’s Data Says Reinfection Doesn’t Increase Risk of Health Issues

In October when the XBB wave hit, Health Minister Ong Ye Kung said that our reinfection rate hit 18%.

However, this local data did not show worsened health issues or illnesses in reinfections, compared to first-time infections.


The percentage of people who suffer from severe illness was 0.2% for reinfections, and 0.3% for first-time infections.

Reinfections are generally mild, especially if you’re vaccinated and remain up-to-date with your boosters.

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Confuses Association with Causation

Professor Dale Fisher, NUH’s senior infectious diseases consultant and the chair for the WHO’s Global Outbreak Alert and Response Network steering committee, said the paper confused association with causation.

For example, just because someone was standing next to you when you fell down, doesn’t mean the person was the cause of you falling down. 

Professor Fisher pointed to this specific statement: “the findings show that reinfection further increases risks of all-cause mortality and adverse health outcomes in both the acute and post-acute phases of reinfection.”


He said that people who were economically disadvantaged and had inequitable health support were obviously more likely to have higher health risks. They’ll also be less likely to avoid repeat infections.

Thus, they may be more likely to die, but it doesn’t mean that it’s due to COVID-19 when they already have a bunch of health issues that could’ve been the cause.

TLDR: this study is heavily flawed, so you shouldn’t panic if you ever get reinfected.

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