Delta ‘rapidly overtaking’ Alpha in COVID-19 variant cases

Delta is fast becoming the dominant variant of COVID-19 cases in the Philippines, according to the Philippine Genome Center. (Photo courtesy of PGC)

By Joseph B.A. Marzan

The Delta variant (B.1.617.2) of the coronavirus disease 2019 (COVID-19) is surpassing the Alpha variant (B.1.1.7) in terms of the number of cases, according to the head of the Philippine Genome Center (PGC).

In a webinar hosted by professional medical groups last Sept. 2, PGC Director Dr. Cynthia Saloma shared the most recent data and other information focusing on the Delta and Lambda (C.37) variants.

The Global Genomic Epidemiology of SARS-CoV-2, which Saloma presented, was based on the Global Initiative on the Sharing of All Influenza Data (GISAID), a database where more than 2 million whole genome sequences of the virus are shared by researchers around the world.

The Philippines has shared a total of about 5,300 whole genome sequences and hopes to upload all 12,000 other genome sequences soon.

Saloma said the GISAID data as of Aug. 31 indicated that while the Alpha variant was the dominant variant detected in the beginning 2021, Delta variant cases rapidly spread since April 2021.

Studies have also shown that the Delta variant was 60 percent more transmissible than the Alpha variant and other COVID variants detected since the disease broke out in Wuhan, China near the end of 2019.

Based on submitted genome sequences, the regional distribution of Delta between Aug. 3 to 31 is almost 100 percent both in the Australian continent and North America, 97 percent in Africa, 92.3 percent in Asia, 88.9 percent in Europe, and 65 percent in South America.

Delta variant cases, which were first found in India in September 2020, have been detected in 146 countries. The earliest sample of the Delta variant in the Philippines was taken on April 24, 2021.

In the Philippines, the PGC has detected 1,789 Delta variant cases, still lower than Alpha (2,395) and Beta (2,669) variants.

The center’s latest report (Aug. 27) indicated that the Delta variant accounted for 516, or 68.98 percent, of the 748 COVID samples recently sequenced in the PGC laboratory.

Alpha variant cases totaled 73, Beta, 81; and Theta, 41.

Saloma said that their data showed a steep increase in sequenced Delta variant cases in the country, from only 5 percent in June 2021 to 48 percent in July.

“Beginning in January, we’ve detected a lot of [non-concerning variants], but eventually, the Alpha and Beta variants were probably causal in the spikes in cases in March, April, and May in the National Capital Region and CALABARZON areas. But eventually, the Delta variant was aggressively overtaking other variants of concern. (sic) This is even more pronounced in the [NCR] in the month of June [where the detection] was around 10 percent, but by July increased by up to 78 percent,” Saloma said.

As to the Lambda variant (first detected in Peru in November 2020), only 33 countries logged 5,084 detected sequences. But unlike Delta variant, Saloma noted a visible decline in Lambda cases.

The first detected case of the Lambda variant in the Philippines was a 35-year-old female from Negros Occidental, whose sample was collected on July 22.

Due to its nature of being heavily resistant to COVID-19 vaccines, the World Health Organization still considers Lambda as a Variant of Interest (VOI), but Saloma said vaccines still help prevent severe Lambda cases and hospitalization.

Due to the global decline in Lambda variant cases, the variant was “not yet a matter of concern”.

“We have only detected one Lambda variant, and we have not yet detected onward transmission, so this is not partly a matter of concern for now,” she said.

But ultimately, Saloma warned that if people do get infected with COVID-19, viral mutations and emergence of new variants will likely continue to be observed.