Keeping the Delta variant at bay

Published June 22, 2021, 12:12 AM

by Dr. Edsel Salvana

60 percent more transmissible, with the Philippines logging at least 13 cases, with one death

Dr. Edsel Maurice T. Salvana

Two months ago, the most horrific scenes of mass cremations were coming out of India. People were dying from lack of oxygen and bodies were washing up on the banks of the River Ganges. Many pointed to the premature declaration of victory by the Indian government over COVID-19. They allowed massive religious festival gatherings and election rallies with little or no physical distancing or the use of masks. The unprecedented spike of infections led to more than 300,000 cases a day, with over 4,000 deaths a day. This has since somewhat abated, but cases remain in the hundreds of thousands and deaths are still in the thousands.

While the poor compliance with public health standards certainly fueled the outbreak, scientists who were just as stunned as everyone else at the level of carnage quickly determined that a new variant of concern was driving the surge. Known as B.1.617.2, the Indian variant, the double mutant, and most recently the Delta variant, this new variant has now been shown to be about 60 percent more transmissible than Alpha (B.1.1.7 or the UK variant). It is driving surges of infection in the UK and the US. It is already the dominant variant in the UK, accounting for 90 percent of the new cases.

Adding to this concern is that COVID-19 cases in the UK needing medical attention included people who had been vaccinated. One third of them had received at least one dose of a COVID-19 vaccine, although only about 6.7 percent were fully vaccinated, defined as at least two weeks from the second dose. The bad news is that partially vaccinated people may not get much protection against the Delta variant, and a significant number of people have been foregoing their second shot for different reasons. The good news is that fully vaccinated people do continue to have a high level of protection.

In the Philippines, we have had 13 confirmed cases of the Delta variant. Fortunately, these were all detected among returning Filipinos who were promptly quarantined and did not pass it on to the community. Four of those Filipinos were under my care and had worrisome clinical courses, with one patient succumbing to the virus after his lungs gave out.

Nine confirmed cases of Delta were from one ship with a history of travel to India, while the other four were returning travelers. Each one of these cases could have seeded the community and killed thousands of people if they had not been intercepted.

Quarantine protocols for travelers entering the Philippines have gone through several iterations. Since the various variants did not originate from the Philippines (except for P.3), almost all new variants are brought in from other countries. The first three cases of COVID-19 in the Philippines came from China. The lineages involved were lineage A (1 case) and lineage B (2 cases). Banning travel from China kept lineage A and B cases out. The next cases in March of 2020 were lineage B.6, with genome sequences most closely matching viruses from India, Japan, Singapore, and the MV Diamond Princess. In June 2020, lineage B.1 and B.1.1 originated from Europe, matching viruses from Germany, the UK, and elsewhere. Clearly, our early attempts at controlling entry of different variants had mixed results.

The safest but most expensive way of preventing entry of new variants is facility-based quarantine for 14 days. Fourteen days is the long incubation period of SARS-CoV-2, and if one does not develop symptoms within this period then the chances of having been infected are miniscule. Unfortunately, it is quite expensive and the policies were tweaked to allow early release if people tested negative on arrival. This is clearly inadequate as someone who acquired COVID-19 on the day of travel will test false negative on arrival. Provisions for continuation of quarantine at home to lessen the cost were formulated, but many did not comply once they were out of the facility. Shortage of tests also meant that instead of the gold standard RT-PCR tests, in some cases rapid antibody tests with poor sensitivity and specificity were used.

In January 2021, in order to prevent the entry of the Alpha variant, a strict 14-day facility-based quarantine was reinstated for returning travelers, especially from countries with the reported variant. This policy was able to intercept many cases, including some with no history of travel to countries that had reported the Alpha variant. The extreme cost of this policy, however, led to it once again being modified to fifth day testing and if negative, release to complete the rest of the 14 days quarantine at home. This was also variably successful, with many local government units unable to provide proper monitoring. With the relaxation of this policy, the Beta variant (B.1.351, the South African variant) was able to enter and spread, contributing to the April 2021 surge.

The latest iteration of testing and facility-based quarantine was a result of a combination of safely shortening facility-based quarantine and maximizing testing yield. Modeling data from the US Centers for Disease Control shows that a 10-day facility-based quarantine, with or without testing, brings the risk of transmission to others by an asymptomatic carrier to less than five percent. An additional four days of home quarantine was added to approximate the 14-day period. It was felt that this protocol was sufficient to keep the variants at bay, including the Delta variant as long as it was uniformly implemented nationwide.

More and more publications are showing that Delta is causing more serious disease and affecting a lot of younger people. Reports out of Guangzhou in China, where Delta has recently gained a foothold, are showing sicker patients and rapid transmission. Several generations of infections are overlapping each other and making contact tracing difficult. If Delta gets into the Philippines before we vaccinate a substantial number of our vulnerable population, the death toll will be devastating. The virus only needs the smallest of openings to wreak havoc. Fully vaccinating everyone will protect us. Until then, we all need to present a united front. There is no room for a piecemeal approach and the actions of one can save or doom us all.