What we know so far about COVID-19 ‘reinfections’

Jodesz Gavilan

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(UPDATED) A study by Hong Kong researchers reports the first case worldwide of reinfection which proves that immunity against COVID-19 'is not lifelong'

Interior Secretary Eduardo Año on Sunday, August 16, announced that he tested positive for the coronavirus, the second time since the pandemic started in early 2020. 

He first got infected on March 31, and recovered at least two weeks later on April 13. 

This new development meant that Año, one of the top officials overseeing the country’s coronavirus response, contracted COVID-19 again after only 4 months. 

What happened to Secretary Año?

In his announcement, Año said he started having flu-like symptoms such as sore throat and body aches on August 13. He immediately went into self-quarantine and got swabbed on August 14.

He received the positive result on August 15.

The Department of Health said it is still studying what happened to Año, to determine whether the result of his latest PCR test is because of the remnants of the virus or that he truly was infected again. 

Health Undersecretary Maria Rosario Vergeire said Año’s case will be examined thoroughly and information will be released to the public as soon as possible.

“We would like to assess him in full, including clinical symptoms, his previous positive result, and technical details of the laboratory results,” she said in a mix of English and Filipino.

While there is still no definite explanation on what exactly happened to Año, Vergeire reminded the public that there are instances when the PCR test detects “fragments of the virus.”

“I just would like to remind everybody that RT-PCR is very sensitive na kahit na weeks after or months after the illness, minsan may nakikita pa rin ng fragments ng virus (even weeks or months after the illness, it can still detect fragments of the virus),” she said. 

This was what happened to Senator Miguel Zubiri, whose swab test prior to President Rodrigo Duterte’s State of the Nation Address in July returned positive. A later confirmatory test yielded a negative result.

The senator first tested positive for COVID-19 in March, first among high-ranking officials, and recovered in April. 

In a letter to Zubiri, as quoted by the Philippine Daily Inquirer, the DOH said that “due to the test’s sensitivity, the PCR result [of the Senator] can be remnant of the virus. It can also be a false-positive result or cross contamination.”

Is it possible to be infected again?

While Año’s case remains unclear, it already begs the question: can a recovered patient get reinfected? 

Scientific institutions are still conducting further studies to determine whether or not a reinfection is possible. At the same time, it is important to know that the lack of a clear answer does not completely discount the possibility of a second infection. 

“There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection,” the World Health Organization said in a scientific brief in April. 

The US Centers for Disease Control and Prevention (CDC), meanwhile, said that it is vital to consider the time period when a person tested positive for the virus again.

“If a positive test occurs more than 3 months after a person’s symptom onset, clinicians and public health authorities should consider the possibility of reinfection,” it said.

Health expert Dr Tony Leachon also highlighted results of recent coronavirus-related studies that “sparked questions about immunity.” 

These include a pre-print study that is yet to be peer-reviewed which found that anti-bodies developed against the coronavirus by patients “declined significantly within 2 to 3 months post-infection.” 

The study conducted by a team led by researchers from King’s College London showed that recovered patients may lose their immunity within months.

“Given that antibodies help to neutralize the coronavirus and are believed to provide people with immunity against the pathogen, those findings have raised alarms among some observers that people may gain natural immunity to the coronavirus for only a few months,” Leachon explained. 

Leachon also said that there is also the possibility that “such patients simply relapse because the coronavirus lies dormant in their bodies and reemerges – an occurrence that’s been seen with some viruses that often result in lifetime immunity, such as the chickenpox virus.” 

But he emphasized that more research is needed to answer why some patients contract COVID-19 more than once.

On August 24, researchers from Hong Kong University’s Faculty of Medicine announced that they’ve identified the first “proven” case of reinfection. The case involves a 33-year-old man who tested positive for the virus after more than 4 months since his first infection.

The forthcoming study analyzed two virus strains and found that they were “completely different.”

Kelvin Kwai-Wang To, microbiologist and lead of the team who conducted the study, told Agence France-Press that the findings “prove that immunity for COVID infection is not lifelong – in fact, reinfection can occur quite quickly.”

Recovered patients show COVID-19 symptoms again. What should they do?

If you are a recovered patient who suddenly showed COVID-19 symptoms again, the steps you need to take will depend on when these symptoms appeared.

CDC said that a person who develops symptoms more than 3 months after the first onset of the previous infection should be retested. 

“Persons with recurrent symptoms after the first 3 months who test positive should be considered infectious and remain isolated until they again meet criteria for discontinuation of isolation or of transmission-based precautions,” it said.

“If a person who has recovered…has new symptoms of COVID-19, the person may need an evaluation for reinfection, especially if the person has had close contact with someone infected with COVID-19,” CDC said. 

If they showed symptoms within the first 3 months, retesting may be necessary if other possible reasons are already ruled out by infectious diseases specialists.

“The person should isolate and contact a healthcare provider to be evaluated for other causes of their symptoms, and possibly retested,” CDC added.

For Leachon, any person should be observant about flu-like symptoms regardless if he or she had prior infection already.

“Science is evolving, medicine is dynamic,” he said. “It would be best to periodically take tests especially with flu-like symptoms post-COVID or not.” 

What should patients do after a COVID-19 infection?

People should continue following minimum health standards set by the government, even if they already contracted and recovered from COVID-19. These include wearing masks and observing physical distancing, among others. 

Observing these precautions is better than nothing, as more studies are conducted about the possibility of reinfection. 

Until there is a clearer picture about second infection, the CDC “recommends that all people, whether or not they have had COVID-19, continue to take safety measures to avoid becoming infected with COVID-19.”

Leachon, meanwhile, urged the public to be “very vigilant” as the battle against the coronavirus in the Philippines continues.

“This virus is unpredictable,” he said. “It’s less virulent than SARS on paper but definitely it’s more transmissible.” – With reports from Agence France-Presse/

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Jodesz Gavilan

Jodesz Gavilan is a writer and researcher for Rappler and its investigative arm, Newsbreak. She covers human rights and also hosts the weekly podcast Newsbreak: Beyond the Stories. She joined Rappler in 2014 after obtaining her journalism degree from the University of the Philippines.