“Examining and reexamining the vaccine results, I’ve gone through stages too—caution, hope, and finally, clarity. We really are that close. The beginning of the end is here.” - Dhruv Khullar, M.D., assistant professor, Weill Cornell Medical College, writer
“How often has the unexpected happened! How often has the expected never come to pass!”
- Seneca, Roman philosopher and statesman, 4 BCE
In the U.S., things look and feel like the COVID-19 pandemic is finally on its way out. Newspaper headlines read: “COVID-19 Cases Hit the Lowest Point in the U.S. Since the Pandemic Began.” Medical articles are appearing bearing titles such as “Concerts May Be Safe to Attend With Proper Precautions.” But before throwing all caution to the wind, I believe we should listen carefully to Dr. Rochelle Walensky, Director of the Center for Disease Control and Prevention, who stated, “I think we would be remiss to say we are out of the woods. This pandemic has sent us too many curve balls and it’s too early to declare victory.” I couldn’t agree more (see my Germ Gems post last October, “COVID-19 Curveballs”). Nonetheless, in this Germ Gems post, I’ll provide evidence to support the case for cautious optimism.
How do we know when a pandemic is over? There have been an estimated 186 epidemics and pandemics in human history. Pandemics are, however, mind bogglingly complex. Therefore, examining how these past pandemics ended is unlikely to be of much value in determining how the COVID-19 pandemic will wind down and eventually end. Adam Kucharski, a professor at the London School of Hygiene & Tropical Medicine and author of The Rules of Contagion,commented on the myriad of factors, such as the virulence of the pathogen, its modes of transmission, the length of time an individual is contagious, and the social networks that each disease exploits, that make it virtually impossible to find a single pandemic that’s a useful guide for predicting the end of COVID-19. As Kucharski said, “There’s a saying in my field: ‘if you’ve seen one pandemic, you’ve seen . . . one pandemic.’”
Mathematical models may be helpful in predicting the end of this pandemic. In her April 29, 2021 New York Times article entitled “The Math That Explains the End of the Pandemic,” Zoe McLaren, an associate professor of public policy at the University of Maryland, explains the principle of “exponential decay.” During the COVID-19 surges, we all witnessed “exponential growth,” that’s when COVID-19 case numbers doubled in just a few days. Exponential decay is the opposite—case numbers halving in the same amount of time. McLaren writes: “The end of the pandemic will therefore probably look like this: A steep drop in cases followed by a longer period of low number of cases, though cases will rise again if people ease up on precautions too soon.” This is the pattern that we’re seeing in the U.S., where case numbers and deaths are rapidly falling. McLaren, however, adds, “Infections begin to taper when herd immunity is reached . . . You shouldn’t expect the road to herd immunity to be smooth, though.”
The bumpy road to herd immunity. The term herd immunity is borrowed from veterinary medicine. The concept is simple and I have addressed this in numerous past Germ Gems posts. Picture a herd of cattle. If a virus infects one cow in the herd and none of the rest is immune, then the virus can spread throughout the whole herd. But as more and more cows get infected and gain immunity, the virus cannot be passed on, and the herd becomes protected. Herd immunity can be achieved through natural infections or by vaccination.
One year ago, few, if any, experts were predicting that by late December 2020 to early January 2021, we’d have three safe and effective vaccines at our disposal to fight COVID-19. Recently, COVID-19 cases, hospitalizations and deaths have plummeted (logarithmic decay) in the U.S. This is due to the development of these three remarkable vaccines and the ambitious vaccination rollout program of the U.S. government. In America, we can therefore be cautiously optimistic that we can, if we are willing, reach herd immunity and control this virus here.
According to Paul Offit, the director of the Vaccine Education Center at the Children’s Hospital in Philadelphia, “The question is not when do we eliminate the virus in this country. Rather, it’s when do we have the virus sufficiently under control?” In the early months of the COVID-19 pandemic, it was suggested that herd immunity would be reached when 60-70% of the population was immune. But with the appearance of more and more viral variants (mutants), the estimate is now 80-90%. We have a ways to go before reaching this goal. As of June 4, 2021, 138 million people (only about 42% of Americans) had been fully vaccinated. Therefore, a number of creative strategies have emerged to reach those who lack access to vaccine and to encourage those with “vaccine hesitancy” or “vaccine apathy.” In Minnesota where I live, the state has initiated a “Summer Vaccine Rewards” program offering certain prizes (ranging from free fishing licenses to state fair tickets) to the first 100,000 people age 12 and older who get their first COVID-19 shot between May 27 through June 30, 2021. While I don’t believe that any of us should need an incentive, I nonetheless applaud any and all efforts to try to get more people vaccinated.
The necessity of vaccinating the world. The herd is not just the U.S.; it extends to all corners of the globe. In a June 3, 2021 article in The New Yorker, “The Peril of Not Vaccinating the World,” staff writer Sue Halpern warns: “Absent a concerted global commitment to vaccine equity, the virus will continue to evolve, and humanity may be consigned to a never-ending pandemic.” She points out that as of early May, less than 8% of the world’s population had received a single dose of COVID-19 vaccine.
Vaccine distribution disparities have been recognized since vaccines became available. In a short period of time, vaccines are going to be available in most, if not all, high-income countries. But the biggest challenge is to provide vaccines at no cost to those living in low and middle-income countries. In April 2020, the Global Alliance for Vaccines and Immunization, a 21-year-old international vaccine alliance, partnered with the World Health Organization (WHO) and the Oslo-based Coalition for Epidemic Preparedness (CEPI) to create COVID-19 Vaccines Global Access (COVAX), an initiative aimed at distributing COVID vaccines equitably around the world. A key component to the success of efforts to vaccinate everyone in the world was to fully fund COVAX. On June 2nd, this goal was reached.
At the meeting of G7 country leaders in early June, Richard Hatchett, Chief of CEPI made a request for sufficient vaccine donations to avert an outcome akin to the 1918-1919 flu pandemic that killed 50 million people globally. For its part, the U.S. recently announced plans to donate 80 million COVID-19 vaccine doses to COVAX. Moreover, the Biden administration is exploring ways to sustain public-private partnerships without abandoning the intellectual property of pharmaceutical companies, which may help provide vaccines to low and middle-income countries.
Are SARS-CoV-2 variants going to be spoilers? Mutant viruses labeled as “Variant of Concern (VOC)” are the most worrisome. (This topic is addressed in my May 19, 2021 Germ Gems post “Vaccines vs. Variants: A Marathon not a Sprint.) They are more contagious and may not be covered by current vaccines. Initially, these variants were classified by scientific names but more commonly referred to by the country where the variant first appeared. For the general public, remembering the scientific name of the variant was an unwieldy task and referring to the variant by a country produced a certain stigma. Therefore, the WHO recently revised their classification system using the Greek alphabet and assigning a letter to each variant based on the order in which they emerged: “Alpha” or B.1.1.7, originated in the UK; “Beta” or B.1.351, emerged in South Africa; “Gamma” or P.1., first seen in Brazil; and “Delta” or B.617.2, which arose in India.
The world is currently struggling to contain the Delta coronavirus. Preliminary evidence suggests Delta may be more resistant to the protection afforded by the Pfizer/BioNTech vaccine. In a June 7 New York Times article, “The Dangerous Delta Variant,” David Leonhardt tells of Britain’s exceptional success in confronting COVID-19 where cases retreated more quickly than in almost any other country. But now the U.K.’s progress is seriously threatened by a major uptick of cases caused by the Delta virus. As Leonhardt wrote: “The increase is a reminder that progress against the pandemic—even extreme progress—does not equal ultimate victory.”
On June 8, the Biden Administration stated that the Delta variant accounts for 6 percent of new infections in the United States. However, the vaccines appear to be highly effective against this version. Dr. Anthony Fauci stated the Delta variant is “essentially taking over” in the United Kingdom. “We cannot let that happen in the United States, which is such a powerful argument” for vaccination, he said.
It’s far too early to tell what impact these already identified VOCs and others that almost certainly will emerge are going to have on national and international COVID-19 vaccine campaigns. But I am cautiously optimistic. I recently read a report entitled “After vaccinating 95 percent of adults, a Brazilian city is returning to normal” that appeared in Science News on June 2, 2021. In this report, I learned of Serrana, Brazil, a city that was in the throes of devastating infections caused by the Gamma variant. The city initiated an experiment whereby it vaccinated 95% of its adult population. The city is now reopening its schools, concerts, and restaurants. This report demonstrates that vaccinations do work in controlling COVID-19 and even viral mutations. We can only hope that “vaccine obstinacy” in the U.S. and other countries will end so that the world will reach herd immunity.
