Elimination of COVID-19 is no longer possible

CLINICAL MATTERS

As the COVID-19 pandemic drags on toward the second half of 2021, one thing is becoming clear. There is only one acceptable long-term solution to living with COVID-19. That solution is widespread vaccination.

SARS-CoV-2, through its variants, has proven that it will be around for a very long time. Hopes to eliminate it completely with hard lockdowns and by isolating whole countries from the world have now proven to be unsustainable. This is mainly because of the emergence of the Delta variant. Countries such as China, which successfully used hard lockdowns, are now seeing resurgent spikes with Delta. Southeast Asian countries such as Thailand and Malaysia that previously crushed their epidemic curves are seeing their worst outbreaks of the pandemic. Australia, which was touted as a model country response earlier in the pandemic, has had to impose crippling lockdowns in its major cities with mixed results. All these experiences are showing that previously best practices against COVID-19 are not as effective against the Delta variant.

Early lockdowns last year in these countries undoubtedly saved millions of lives. In the Philippines, the March 2020 lockdown is estimated to have saved at least 200,000 Filipinos. The original Wuhan SARS-CoV-2 virus had an R0 (R naught) of 2.4 to 2.6, meaning each infected case could infect between two to three people at a time. Only lockdowns were initially effective in stemming exponential spread at the start of the pandemic. This was the only way to protect the healthcare system and prevent excess mortality at that time.

Countries that did not lock down early or hard enough, such as many European countries, Brazil, and the US, saw case fatality rates as high as 10 percent in the first half of 2020. This was because overwhelmed healthcare systems were unable to cope with the sudden influx of severely and critically ill patients. As healthcare systems adapted by adding capacity, and medical care for COVID-19 became standardized, mortality rates started to drop. Use of masks and other public health interventions started to slow down transmission rates.

When the first vaccines were shown to be safe and effective in December 2020, there was much optimism that the end of the pandemic was near. Countries that had access to enough supply like Israel, UK, and the US embarked on unprecedented immunization programs and rapidly saw their case numbers and deaths drop. The rise of the variants of concern did give some pause especially with Beta in the first quarter 2021, which was showing signs of vaccine escape in neutralization antibody studies.

When the first transmission blocking studies for the mRNA vaccines came out, the news was very good. Pfizer and Moderna vaccines decreased asymptomatic and symptomatic disease by 90 percent. Studies on breakthrough infections for Pfizer also showed that those who did end up with infection despite full vaccination had low viral loads and were unlikely to transmit to others. Data from Astra and Sinovac were likewise promising, decreasing transmission by about 70 percent or more.

When Delta emerged from India, the magnitude and speed of the increase in cases caught everyone by surprise. An R0 for Delta of five to eight eventually emerged—this makes it almost as contagious as chicken pox. In addition, early data from the UK showed that partial vaccination was only about 30 percent protective against needing healthcare intervention, but full vaccination continued to prevent about 90 percent of severe disease.

Data from Israel also showed that vaccines had decreased efficacy in preventing clinical disease from Delta, but that these continued to prevent severe COVID-19 and death at a very high level. Deaths in highly vaccinated countries continued to remain low, despite rapid rises in caseloads.

One other finding that Delta upended was that vaccination decreased the risk of transmission. Preliminary studies on breakthrough infections showed that because viral loads from Delta are up to 1,000 times higher than for other variants, vaccination did not decrease infectivity as previously seen with non-Delta virus.

With the drawn-out nature of the pandemic plus the more contagious Delta variant, the equation has fundamentally changed. This much is clear: It is no longer possible to completely eliminate SARS-CoV-2 in the near future.

The one bright spot we are seeing is that vaccination continues to protect against severe disease and death. While the vaccines have become less effective for preventing transmission and clinical disease from infections caused by variants, enough vaccine activity is retained to decrease the risk of severe disease by about 90 percent. Since the current vaccines are no longer blocking transmission as effectively as before, elimination is no longer achievable with the current set of vaccines. This changes the calculus for countries that are trying very hard to balance health and economy.

Consider the Philippines where about 60 percent of deaths have come from ages 60 and above despite making up only 20 percent of COVID-19 confirmed cases. The collective COVID-19 mortality for this population is about 10 percent. If we can vaccinate all seniors against COVID-19, their death rate goes down to one percent. Still terrible, but much more manageable.

For the rest of the population below 60, the collective mortality rate is about one percent. With vaccination, it goes down to 0.1 percent—which is about the same for the flu. We don’t lock down the country when there is a flu outbreak.

So how do we live with Delta in the meantime?

1. For those above 60, get vaccinated now. After you are fully vaccinated, you still need to limit trips outside the house and wear masks and other mitigating measures. Your risk of death if you have breakthrough infection is still one percent, but that is 10 times less than it was without vaccination. If people around you are vaccinated as well, the risk goes down further. While community transmission is high, it is best to stay home if possible. This is also true for those with comorbid collection who have added risk even if they are below 60.
2. For those between 18 and 60, get vaccinated as soon as possible. This turns COVID-19 into a disease no deadlier than the flu—from a one percent fatality rate to a 0.1 percent fatality rate. In a way, once you are vaccinated the pandemic has ended for you (if you don’t have comorbid illnesses). Continue wearing masks and practicing other mitigating measures to protect those around you, especially the unvaccinated and the elderly who are at higher risk for severe disease.
   
   
3. For those below 18, the vaccines are coming but we need to be a bit more patient. The risk of death for an unvaccinated person below 18 year old is about 0.1 percent, the same as the flu. We need to finish vaccinating the vulnerable populations first. In the meantime, use your mask and face shield if you go out for essential things.

If we vaccinate all of the vulnerable and a significant number of the rest of the population, severe COVID-19 numbers will remain manageable, and we won’t have to lock down ever again. There is also the hope that better vaccines may yet be developed, and boosters specific to Delta and other variants that are currently in clinical trials prove more effective. In the meantime, Delta has changed the strategy. In this battle against the pandemic, the next move is ours to make.