The Delta variant is the most transmissible yet

CLINICAL MATTERS

Dr. Edsel Maurice T. Salvana

With the accelerating rollout of vaccination programs worldwide, things were looking up for a pandemic-weary world in March 2021. After a year of living in fear of COVID-19, the end was in sight. It looked like it was only a matter of time before COVID-19 would be defeated. Israel was showing the way, with its rapid vaccination program causing a marked decrease in cases, hospitalizations, and deaths from COVID-19. Then the surges happened.

The Indian surge was horrific in its scale. Mass scenes of burning bodies and people gasping for breath looking for oxygen were the stuff of nightmares. Initially, the surge was thought to have just been because of the premature relaxation of public health measures. The Khumb Mela religious festival drew millions of devotees, with few practicing protective measures against COVID-19. As genomic sequencing caught up with the surges, it became clear that an additional factor was at play. A new variant termed B.1.617 was becoming dominant. In Britain, which has a strong genomic surveillance network and a large ethnic Indian population, they determined that this variant from India was three variants: B.1.617.1, B.1.617.2, and B.1.617.3. Among these, B.1.617.2 was the most concerning because it seemed to be the most contagious.

Over time, B.1.617.2 was recognized as a variant of concern by the World Health Organization. It was given the designation “Delta” variant in accordance with the new convention of WHO to avoid naming variants from the places they were first discovered as a way to prevent stigma. Since it was the fourth variant of concern, it was given the name of the fourth letter of the Greek alphabet.

Delta, which seems to be the most transmissible variant yet, is aptly named. One tongue-in-cheek joke is that the WHO shouldn’t have named it after an airline (Delta Airlines is the biggest carrier in the US) because now it has “wings.” More appropriate though is the observation that the letter Delta is used as a symbol in scientific literature to denote change. And change this variant did. Even as it caused surges across the world, it has mutated again into a “Delta plus” variant.

Delta plus, or B.1.617.2.1 or AY.1, is pretty much the Delta variant with one more mutation of concern. The K417N mutation on the spike protein may help it evade immune responses. This has not yet been confirmed, but if proven, it will add yet another dimension to the already dangerous repertoire of the original Delta variant.

For now, the best defenses against Delta and Delta plus are strong border controls, stringent public health standards, and rapidly accelerating vaccination programs. Strong border control will keep the variants out of the community. A strict 10-day facility-based quarantine plus four days home quarantine virtually eliminates the risk of a false negative asymptomatic carrier from passing on the virus to the public at large. Even if some variants eventually do get through this cordon, this strategy will delay entry and buy time to ramp up vaccination rates.

Face mask, face shield, and physical distance remain the cornerstones of protection, especially for the unvaccinated. With reports of transmission of the Delta variant with fleeting contact much less than the usual 15 minutes of close contact, each added layer of protection can mean the difference between containment and an outbreak. Finally, vaccinations seem to still work very well against the Delta variant for as long as one is fully vaccinated. There have been reports of breakthroughs with partially vaccinated individuals, and so all efforts should be made to fully vaccinate everyone who is eligible.

In the meantime, misinformation is rampant on the efficacy of COVID-19 vaccines against the Delta variant. There have been many misleading articles that undermine vaccine confidence. Some articles and posts attack vaccines by its country of origin by cherry-picking data, while others engage in scaremongering by exaggerating known adverse effects.

Before concluding that a particular vaccine is or is not working against COVID-19, these are the most important questions that need to be asked:

1. Are the people who are getting sick vaccinated or unvaccinated?

This is a real no-brainer. For instance, there is currently a surge of Delta cases in Israel. On closer look, unvaccinated people are getting sick at nearly 30 times higher rates than those who are vaccinated. Vaccinated people with breakthrough infections are usually asymptomatic or have mild disease and do not need hospitalization.

2. What is the denominator?

There was an inflammatory article about Indonesian healthcare workers getting sick after a Sinovac jab with “dozens” getting hospitalized. What it leaves out is that over 5,000 healthcare workers were vaccinated in the outbreak area. How many were exposed? How many unvaccinated people got sick? What are the exact numbers of those who got sick, those who got hospitalized, and those who died? Were they partially or fully vaccinated? If it is true that 5,000 healthcare workers were exposed but only 350 got sick, then effectiveness is still over 90 percent.

3. What is the vaccination rate in the country?

An article from a usually reliable publication had a headline saying that cases were surging in countries that used the Chinese vaccines. It leaves out the ongoing surges in the UK, the US, India, and Israel where Chinese vaccines aren’t used. How many of those who got sick were actually vaccinated, and how many were fully vaccinated? Were there many deaths among those vaccinated? These answers are needed before concluding that a vaccine isn’t working.

Disinformation and misinformation are spreading at a fever pitch. Fake news, combined with the Delta variant, can kill a lot of people. Vaccines are a public good and they all work, as long as one is fully vaccinated. Combining best practices for keeping the Delta variant out and maintaining vaccine confidence are the keys to victory. The virus may do its best to change, but it will not withstand a sustained onslaught of science-based interventions.