MANILA, Philippines — The World Health Organization (WHO) said more studies are needed to be done to determine how long a person’s immune response against the coronavirus that causes COVID-19 could last after Hong Kong reported the first documented case of reinfection in a 33-year-old man.
Maria Van Kerkhove, the WHO health emergencies program’s technical lead, said that while a person who contracts SARS-CoV-2 does develop an immune response, it is still unclear to this day “how strong and for how long that immune response lasts.”
Antibody response
This was why she said the WHO had advised countries to do sequencing of the virus to better understand how the disease can affect the population, including those who have already been infected.
In the Hong Kong patient’s case, researchers from Hong Kong University found a “24-nucleotide difference” in the makeup of the virus he first contracted in March to that of the virus he got in August.
“But we need not jump to any conclusions to say, even if this is the first documented case of reinfection it is possible of course because with our experience with other human coronaviruses and the MERS coronavirus and the SARS-CoV-1 coronavirus we know that people have an antibody response for some time but it may wane,” Kerkhove told reporters in a virtual briefing.
“We really need studies to be conducted so that we really understand what this immune response looks like. But I don’t want people to be afraid. We need to ensure that people understand that when they are infected, even when they have a mild infection, that they do develop an immune response,” she added.
Kerkhove noted that with regards to the Hong Kong patient, scientists would still have to determine if he did develop a neutralizing antibody response during his first infection, “which is what will protect [you] from the infection.”
In the Philippines, the Department of Health (DOH) asked the public to exercise caution in tagging someone as having been reinfected with the virus, such as Interior Secretary Eduardo Año and Philippine General Hospital doctor Karen Senen.
Senen tested positive again for the virus in July, days after she was discharged. She died on Sunday.
“We still do not have enough evidence to state that reinfection is really occurring. We are already looking into all the circumstances. We are studying and mapping out the international experiences so that we can have appropriate evidence and we can give accurate information,” Health Undersecretary Maria Rosario Vergeire said.
As of this reporting, the DOH has yet to release information on whether sequencing of the virus that Año and Senen contracted is already being conducted.
Earlier, Vergeire said an assessment of Año’s clinical symptoms and technical details of his laboratory results were being done. She noted that because of the sensitivity of the RT-PCR (reverse transcription polymerase chain reaction) test, it was likely that what was detected in him was the remnant of the virus.
Dr. Edsel Salvana, infectious disease expert and DOH technical advisory group member, said that tests can also return as false positives if there is contamination from batch testing or from the positive control sample. Theoretically, he said, a patient could have also inhaled the virus.
“This can theoretically happen when someone is exposed to a positive case who is shedding and is immediately swabbed. There is no guarantee the patient will get the disease because there might not be enough virus to cause the disease, the virus is no longer infectious, or the immune system is able to clear without any clinical disease setting in,” Salvana said in a Facebook post.
On Tuesday, the DOH recorded an additional 2,965 cases, pushing the national caseload to 197,164. Of the cases submitted by 86 of 109 accredited laboratories, 2,434 got sick between Aug. 12 and 25, while 365 fell ill between Aug. 1 and 11.
Metro Manila accounted for more than half of the new cases, or 1,575. A far second was Negros Occidental with 237, followed by Laguna (151), Cavite (129) and Batangas (95).
Recoveries
The total number of people who have recovered from COVID-19 climbed to 132,396 with the recovery of 368 more patients.
The death toll, however, rose to 3,038 as 34 patients succumbed to the severe respiratory disease, leaving 61,730 active cases, of which 91.6 percent were mild, 6.1 percent asymptomatic, 0.9 percent severe, and 1.4 percent critical.
Of the newly reported deaths, 26 died this month, seven in July, and one in June. Twenty of the fatalities were from Metro Manila, four from Central Visayas, three from Calabarzon, two from Bicol, and one each from Northern Mindanao and Mimaropa. A repatriate was also listed to have died from COVID-19. INQ