• Experts have presented a case study of a 90-year-old woman in Belgium who was simultaneously infected with both the alpha and beta strains of Covid-19.
• The woman had not been vaccinated against Covid-19.
• Experts say the phenomenon needs further research.

LONDON — It is possible to be infected with two different strains of the coronavirus at the same time, experts say, after the case of an unvaccinated elderly woman who was found to be infected with both the alpha and beta variants of Covid-19.

The 90-year-old woman died in a hospital in Belgium in March. Experts presented the case study at the European Congress of Clinical Microbiology & Infectious Diseases this weekend, saying it is believed to be the first known case of a double infection and underscores the need to be alert to this possibility.

The woman, whose medical history was unremarkable, experts said, had been admitted to hospital in Aalst, Belgium, in early March after a spate of falls. She tested positive for Covid-19 on the same day and then developed rapidly worsening respiratory symptoms. She died five days later. Genome sequencing of samples from the woman confirmed she was infected by the two variants.  

It's unknown how and when the woman, who lived alone and received nursing care at home, became infected.

She had not been vaccinated against Covid-19. Studies show that the main vaccines in use in the U.S. and Europe (the Pfizer-BioNTech, Moderna and AstraZeneca-University of Oxford shots) are effective against the Covid variants that have emerged, preventing most hospitalizations and deaths. 

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"This is one of the first documented cases of co-infection with two SARS-CoV-2 variants of concern," Dr. Anne Vankeerberghen, lead author of the case report and molecular biologist at the OLV Hospital in Aalst, said in a statement.

She said that as both variants were circulating in Belgium at the time, the woman was likely to have been co-infected by two different people.

"Whether the co-infection of the two variants of concern played a role in the fast deterioration of the patient is difficult to say," Vankeerberghen added. "Up to now, there have been no other published cases. However, the global occurrence of this phenomenon is probably underestimated due to limited testing for variants of concern and the lack of a simple way to identify co-infections with whole genome sequencing."

In January 2021, scientists in Brazil reported that two people had been simultaneously infected with two different strains of the coronavirus — the gamma variant first identified in Brazil and a variant currently under investigation which had been discovered in Rio Grande do Sul — but the study has not yet been published in a scientific journal. Previous research has reported people infected with different influenza strains.

As the coronavirus pandemic has progressed a handful of variants have emerged that have proved to be far more transmissible than the "original" strain of Covid, which emerged in China in late 2019.

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The alpha variant, for example, was detected in southeast England last fall and went on to dominate the world. Now, it is being supplanted by the extra-infectious delta variant, first identified in India in April. Another variant emerged in South Africa in December, known as the beta variant.

The World Health Organization's last weekly epidemiological report on July 6 said that the alpha variant had now been reported in 173 countries, territories or areas, and the beta variant in 122 countries. Delta has been detected in 104 countries to date.