The study, led by Khyber Medical University vice-chancellor Prof. Ziaul Haq, found that a 41-year-old healthcare worker working in Islamabad tested positive for the coronavirus on June 6 with flu-like symptoms and was cleared of COVID-19 on June 19 with reactive antibodies, according to the Pakistani newspaper Dawn.
But four and a half months later, the same worker was found to be once again infected with the virus with severe symptoms and non-reactive antibodies.
The study, titled "COVID-19 reinfection in Pakistan" was published in the Journal of the Ayub Medical College, Abbottabad.
“It is not clear yet whether SARS-CoV-2 infection produces long-term immune protection or a short-lived immunity that would fade with the passage of time,” said Haq, according to Dawn.
"I repeat my stand: we shouldn’t declare a premature victory against coronavirus and [instead should] continue with the preventive measures regardless of the age, comorbidity or previous infection,” added Haq.
Cases of suspected reinfection were reported in Pakistan in October and have been reported worldwide in recent months, with some patients experiencing more severe symptoms or even dying after the suspected reinfection. It remains unclear how long immunity lasts with the novel coronavirus and how common reinfection is.
Health minister of Pakistan's Sindh province, Dr Azra Pechuho, stated in October that asymptomatic patients were testing positive again for the coronavirus with severe symptoms.
“People should religiously follow precautionary measures, as the second attack of the virus caused chronic infection and complications, especially in elderly people,” said Pechuho, according to the Pakistani newspaper, The News.
The leader of the Pakistan People's Party, Rashid Rabbani, died after contracting COVID-19 for a second time within a period of six months, according to Pechuho, who added that "many people" were not forming antibodies after being infected.
IN OCTOBER, a case report published by Oxford University Press reported that an 89-year-old woman from the Netherlands died after she was infected with the novel coronavirus for a second time. This marked the first recorded case of a reinfected patient dying due to the virus.
The woman suffered from a rare white blood cell cancer and, although she was not tested in between the two infections to see if she was negative for the virus, researchers found that the viruses in the two instances of infection were different strains.
A 25-year-old patient with no underlying conditions also had a more severe case of COVID-19 after he was reinfected.
"Previous exposure to SARS-CoV-2 might not guarantee total immunity in all cases. All individuals, whether previously diagnosed with COVID-19 or not, should take identical precautions to avoid infection with SARS-CoV-2. The implications of reinfections could be relevant for vaccine development and application," wrote the researchers in the Oxford University Press publication.
A recent study in Iceland showed that antibodies to the novel coronavirus didn't decline within four months of infection.
The Dutch patient and the patient in Nevada were both reinfected within two months.
Some Israelis who seemingly recovered from COVID-19 and then fell sick with symptoms a second time told Channel 12 in September that the second round was more difficult.
Prof. Arnon Ofek, deputy director-general of Sheba Medical Center, told Channel 12 that while this kind of situation is relatively rare, it is showing up in literature around the world.
"The first case was in Hong Kong, but there were also cases in Nevada and other places. Some of the cases were lighter but some were more severe."
"We don't really know everything about the virus and it will still surprise us in many things. In the end, immunity is created but it is different between people. We believe that there is a degree of protection," said Ofek. "This also has importance regarding the vaccine: We know that people will need two doses and that we will have to vaccinate again in X [amount of] time."
Cases of suspected reinfection with the novel coronavirus have been reported multiple times in Israel, with the first case reported as early as May.
Celia Jean and Reuters contributed to this report.