Fish in a Barrel
Last January, Dr. Michael Olsterholm, the Director of the Center of Infectious Disease Research and Policy at the University of Minnesota, warned that the United States would experience a significant surge in COVID-19 cases starting around the end of March when the more transmissible Alpha variant of the coronavirus was projected to become dominant. His warning was timely and prompted the Biden administration to accelerate the pace of the nation’s vaccination program which reduced the feared surge into a minor and short-lived upward tick in the daily number of confirmed cases. Now, Dr. Olsterholm and other epidemiologists are predicting another surge in coronavirus infections to arrive within the next two months. This surge will accelerate in the early fall as cooler weather descends on the nation and the even more virulent Delta variant of the virus is expected to become the dominant strain. With the nation rapidly approaching President Biden’s goal of vaccinating 70% of Americans, is this just another case of the doctors crying “wolf.” The answer lies in the relative danger posed by the Delta variant and the future prospects of the Biden administration’s efforts to further expand the reach of its vaccination program.
The Delta variant of the coronavirus was first detected in India where it quickly became the dominant strain. According to the Johns Hopkins website, India has recorded over 30 million confirmed cases of the virus and has suffered just under 400,000 COVID deaths, many of which were attributable to the Delta variant. That variant has now spread to 80 countries including the U.K where it currently represents 90% of that country’s new COVID cases, supplanting the Alpha variant which had been the U.K.’s dominant strain. Similarly, Israel is now reporting that 70% of its new COVID cases are products of the Delta variant. While the Alpha variant was reported to be 50% more transmissible that the original strain of the coronavirus that ravaged the U.S. during 2020, the Delta variant is thought to be 70% more transmissible than the Alpha variant. That assessment is evident in its remarkable spread in the U.S. since it arrived in the early spring. By June 1st it represented 2% of all new U.S. COVID cases and it now represents 25% of all new U.S. cases.
The Delta variant, in addition to being highly transmissible, presents a more serious health threat than earlier strains. Whereas only 8% of those Americans infected during 2020 required hospitalization, the hospitalization rate of individuals infected with the Delta variant is more than twice that. Fortunately, the monoclonal antibody treatment that helped former President Trump recover from his COVID infection seems to be effective in neutralizing the Delta variant – but that treatment is still considered experimental and may only be available to a small portion of those who become infected. Similarly, it has been reported that the current vaccines are effective in preventing Delta variant infections although their effectiveness has been determined to be significantly less than against earlier strains of the virus. Their reduced effectiveness against the Delta variant is evident from the fact that Israel has recently reported that 50% of its newly infected adults had previously received the Pfizer vaccine. This has prompted the World Health Organization to recommend that face masks continue to be worn even by those who have been fully vaccinated.
Underlying predictions of a fifth surge of the virus is the fact that the U.S. has only fully vaccinated approximately 156 million Americans with an additional 26 million having received a first dose of one of the mRNA vaccines. In addition, approximately 34.5 million Americans have been confirmed to have been infected by the virus and are believed to have thereby achieved immunity. This leaves the approximately 115 million remaining Americans who are currently potentially vulnerable to becoming infected with the COVID-19 virus. That number should be reduced by the number of those who have contracted the virus without having their infections recorded. While the number of unrecorded infections remains unknown, the best current estimate is that there are still between 30 and 80 million Americans who remain subject to becoming victims of the Delta variant. That means that the potential number of COVID infections still to be experienced in the U.S. could potentially exceed the roughly 34.5 million U.S. COVID infections that have already been confirmed.
According to the CDC, roughly 75% of Americans aged 65 or older have been fully vaccinated and another 10% have received a single dose of the Pfizer or Moderna vaccines. Vaccination rates for those under the age of 65 drop off quickly with only about 55% of Americans between the ages of 50 and 64 having been fully vaccinated and another 9% having received a single dose of a vaccine. Going down the age scale, vaccination rates continue to fall steadily with only 40% of Americans between the ages of 18 and 24 having been fully vaccinated. As might be expected from these figures, the demographics of those currently being infected run in the other direction, with the percentage of those newly infected rising in inverse relationship to their age. Stated another way, the younger you are, the less likely you are to have been vaccinated and the more likely you are to become infected. This means that the vast majority of the new infections will be experienced by those under the age of 40.
There are a number of reasons why the Delta variant may precipitate a new surge in virus cases. First, there is a strong possibility that the nation will not be able to achieve the 80% immunization level generally thought to be required to achieve herd immunity (i.e., when the spread of the virus slowly comes to a halt because number of persons to whom each infected person is able transmit the virus is less than 1). This is because slightly over 20% of adult Americans have expressed their intention not to become vaccinated. Some are simply fearful that they might have an adverse reaction to the vaccine or believe that it is possible to contract the virus from having been vaccinated. Others fear that the vaccine may cause other health issues. Still there are many others who simply feel no need to protect themselves. There are even those that fear that the nation’s COVID vaccination program is a cover for a secret government operation to limit their freedom by injecting them with some chemical or device that can control their future actions. Although the federal and state governments are trying to overcome these concerns by offering incentives to become vaccinated, it’s unlikely that those incentives will be sufficient to encourage significant numbers of these individuals to become vaccinated.
Another problem impeding the nation’s efforts to achieve herd immunity is that none of the available vaccines are currently approved for children under the age of 12. This group currently represents approximately 15% of the nation’s population. While clinical trials are now underway to test the available vaccines in children, it may take several more weeks, if not months, before those vaccines are approved for use in children under the age of 12. As long as young children remain unvaccinated, they will be free to contract and transmit the virus among themselves and to pass it on to friends and family members who have not been vaccinated.
While it’s generally assumed that herd immunity will take effect when 80% of Americans have become immune to the virus, that will only be true for a pathogen like the Alpha variant that tends to be transmitted to 1.5 people by every infected person. It does not apply with respect to a pathogen like the Delta variant which on average is thought to be transmitted to 2.3 people by each infected person. Such a highly transmissible pathogen will require at least a 90% level of community-wide immunity before each infected person will infect less than one other person.
Another cause for concern is that as long as the virus continues to spread, it will continue to mutate. The World Health Organization has already identified over two dozen variants of the coronavirus which like all organisms operates under Darwinian principles with each more successful variant rapidly supplanting its predecessors. While it’s tempting to think that the Delta variant is the most lethal and transmissible of the COVID-causing pathogens, epidemiology offers no assurance that a more virulent variant won’t evolve. On the contrary, most epidemiologists will tell you that the longer the Delta variant continues to spread, the higher the odds that a more virulent variant will not only evolve but will be able to elude our current vaccines and be impervious to our therapeutics. One potentially more dangerous variant (dubbed the “Delta-plus” variant) has already been detected in the U.S.
Even in the unlikely event that our nation were to achieve the requisite herd immunity threshold, there will still be pockets of Americans where the percentage of immunized individuals would be well short of that level. This is likely to be true in rural areas of the country and in certain metropolitan areas with a high population of groups less likely to become vaccinated. The CDC has created maps revealing the percentages of vaccinated individuals in each of the nation 3,300+ counties. While more than half of the populations in most of the nation’s counties have already been immunized, there are still hundreds of counties, particularly in the southern states, where the immunization rates are under 30%. Peoples living in those counties are thus like fish trapped in a barrel for a virus that can be transmitted as readily as the Delta variant. This will be doubly true in metropolitan areas where the rate of social interactions tends to be greater.
This still leaves uncertain just how severe the predicted next surge of the virus will be. That will be governed by three factors: (1) the number of Americans who currently possess no immunity to the virus, (2) the number of Americans who will be vaccinated in the next two months and (3) the other steps that will be taken to slow the spread of the Delta variant.
As explained above, we don’t actually know the extent of the nation’s vulnerable population because we don’t know the number of persons infected with the virus whose infections were not confirmed. Earlier predictions were that it could be as high as 8 times the number of confirmed cases of the virus. That number now seems far too high because the virus is still able to find new victim. Even a ratio of 5 times the number of confirmed infections which would leave at least 10 million Americans still vulnerable to the virus (depending on the rate of overlap between those infected and those who have been vaccinated) is probably too high an estimate. While a 3 or 4 to 1 ratio seems within the realm of probability, even those estimates can only be explained by assuming that a large percentage of the people with unconfirmed infections were asymptomatic. Furthermore, since many such individuals were also likely to have become vaccinated the number of additional immune individuals represented by unconfirmed infections would actually be much lower. This leads me to believe that there remain upwards of 80 million Americans who currently remain vulnerable to the COVID-19 virus.
The next big unknown is how many Americans are likely to be vaccinated in the next 60 days. The sad answer seems to be that only a few million who have not already received their first dose of a COVID vaccine will become immunized. That’s largely because over 50% of potentially vulnerable Americans are children and because a significant percentage of adult Americans have expressed their intention not to be vaccinated. This means that the current efforts to encourage the remaining Americans to become vaccinated are not likely to be successful. The Biden administration’s vaccination program did a remarkable job in mitigating the fourth surge of the virus this spring, but it did so by exhausting the “low hanging fruit.” Convincing those remaining to become vaccinated will be very difficult which explains why most states have severely reduced their requests for vaccines and why the U.S. is now offering to send much of it current vaccine supplies to other countries. The one thing that could significantly change this equation would be an expedited effort to approve the vaccines for use in children under the age of 12. This possibility, however, also seems remote. To understand why, one only needs to imagine the political fallout that would result if a relaxation of the FDA’s approval process resulted in even a few adverse reactions in young children.
A rapid spread of the Delta variant could also be slowed if state and local governments were to impose social distancing and face mask requirements; however, such actions also seem to have a low likelihood. Those states with a low percentage of vaccinated residents are also the states that have resisted imposing restrictions to slow the spread of the earlier strains of the virus. They include, among others, the States of Georgia, Arkansas, Alabama, Louisiana and Mississippi with only 43%, 41%, 39%, 38% and 36%, respectively, of their residents having received at least one dose of the available vaccines. Equally importantly, state-wide action is unlikely within any state with communities where the potential spread of the virus is low. In addition, because few states will be imposing restrictions to slow the spread of the virus, it would be politically difficult for county and municipal governments to impose such restrictions on their residents. Moreover, even if restrictions were to be imposed in communities particularly vulnerable to the Delta variant, the level of compliance would likely be low.
These factors strongly indicate that remedial actions against a potential fifth surge of new COVID infections are not likely to be employed or, if employed, likely to prove effective. This means that the magnitude of that surge will essentially be a function of the size of vulnerable segments of the population, something that remains largely unknown. If only 30 million Americans remain vulnerable, the daily rate of confirmed cases might reach as high as 25,000 which was the peak daily number of cases experienced during the first surge of the virus that that took place in the spring of 2020. If the number of vulnerable Americans exceeds 50 million, the peak number of daily confirmed cases could reach 70,000 matching what the nation experienced in last summer’s surge. We can only hope that potentially vulnerable individuals will recognize just how precarious their situations are and do what is necessary to protect themselves—staying at home, wearing masks, and above all getting vaccinated.