Rapid change on the public health front has been a hallmark for over a year, and recent weeks have brought a particular flurry of developments in the COVID-19 pandemic.
While a number of these are positive, the pandemic threat is not yet contained, and continued, well-chosen actions remain essential if we are to transition as quickly as possible to a safer, productive future.
To help put these matters in perspective, the discussion below outlines the interrelated issues of the tremendous personal and societal value of COVID-19 vaccination; the implications of new coronavirus variants; and how safeguarding health in the modern world depends on controlling the pandemic not just in individual countries but across the globe.
These comments are based on the best current information, but understanding will continue to advance through the massive research and public health efforts against the pandemic. Accordingly, we strongly recommend following a broad mix of well-validated information sources on these topics.
Vaccines: Society’s lifesaver in the pandemic sea
The irreplaceable bright light guiding us to the end of the COVID-19 tunnel has been the unprecedently rapid development of multiple safe and effective SARS-COV-2 vaccines. Expanding vaccination to the highest possible percentage of the population is the indispensable path to future safety for individuals, families, the nation and the world.
All three vaccines approved for use in the U.S. are highly effective. The two-dose Pfizer and Moderna vaccines have an exceptional 94-95% efficacy in preventing COVID-19 illness.
Similarly, in clinical trials, by four weeks after vaccination (a reasonable period to develop immune responses), the Johnson and Johnson vaccine almost completely prevented serious COVID-19 requiring hospitalization. Real world studies from the U.S., Israel, Italy and elsewhere also show that COVID-19 cases fall in highly vaccinated populations.
The strong safety results from the above clinical trials has been further underscored by the hundreds of millions of people who have now received these vaccines with no adverse effects.
The Pfizer and Moderna vaccines have outstanding safety records. Use of the Johnson and Johnson (J&J) vaccine was briefly paused in the U.S. to review blood clots that occurred in a very few women after receiving the J&J vaccine. The frequency of this event (whose possible linkage to the vaccine remains uncertain) was only seven events per million vaccinated women 18-49 years old. For women over 50 and men of all ages, the event was even rarer. Accordingly, CDC reinstated use of the J&J vaccine — with clear notifications about this issue — since the known benefits of this vaccine in preventing COVID-19 deaths and long-term health problems vastly outweigh the rare frequency of this issue. Importantly, none of the vaccines contain or were derived from the actual COVID-19 virus, so they cannot give you COVID-19.
Recent approval of the Pfizer vaccine for children 12 years and older is similarly based on stringent safety and efficacy testing in adolescents. This is a crucial development since thousands of children have required hospitalization for COVID-19 and hundreds have died from it. Clinical trials of COVID-19 vaccination of younger children are in progress now, and it is hoped that their vaccination might be approved within this year.
Normal reactions to the vaccines – when they occur – are mild (sore arm, headache, etc.), usually only last for a day or so, and are expected as indications that the vaccines are functioning as intended to prime the immune system against SARS-CoV-2. Clinical trials and real-world experience show that vaccinated people become highly protected whether or not they experience such noticeable reactions.
Herd immunity or not, more vaccination is always better
Much has been written about “herd immunity” — the collateral effects by which high vaccination rates partly protect even susceptible, unvaccinated members of a community, slowing disease spread. Since SARS-CoV-2 spreads through unvaccinated individuals, as vaccination rates increase, more and more contacts of an infected individual are with resistant vaccine recipients, leaving the virus fewer chains of transmission to reach susceptible individuals.
Many news articles have focused on whether the U.S. can reach a vaccination rate of 70% or higher, which some estimate would confer “herd immunity” effects. While many project that the nation will reach and exceed these levels, such numbers are only estimates.
“Herd immunity” is not an all or nothing state that turns on at a specific threshold, but a sliding scale of protection that increases with increasing vaccination rates. The more people are vaccinated, the harder it will be for the virus to spread, and new cases will decline. Any additional increment in vaccination will provide additional, much-needed protection for all.
Thus, for those interested in protecting themselves, family members and their community, by far the most important action that they can take is to become fully vaccinated, and to encourage others to do the same. Moreover, while many children, essential workers, and other vulnerable groups still need to be vaccinated, it will remain important to use good judgement about continuing other safety measures. This includes distancing and mask use when in groups including people who are unvaccinated or whose vaccination status is unknown.
SARS-CoV-2 variants: Origin, spread, pathogenicity and vaccine control
Since late 2020 we have seen the repeated emergence of new SARS-CoV-2 variants with enhanced transmissibility. Such variants arise because SARS-CoV-2 and other RNA viruses mutate and evolve at unusually high rates. Variants with enhanced person-to-person spread outgrow competing virus types.
A variant named B.1.1.7 that arose in the UK last December quickly spread to the U.S. and is currently the most prevalent COVID-19 strain here. Other variants of interest have emerged in South Africa, Brazil, the U.S. and India. The increased transmissibility of such variants increases the chance of new waves of infection. Enhanced spread by a variant recently recognized in India, B.1.617, may be contributing to the intensity of the pandemic there.
To date, the COVID-19 vaccines authorized for use in the U.S. appear able to control recognized SARS-CoV-2 variants of concern. However, as the virus continues to mutate, new variants could emerge that are not well-controlled by current vaccines. For this and other reasons, it may be necessary in future to provide booster shots or new vaccines tailored to further emerging COVID-19 variants.
The good news is that the recent development of vaccines against the original SARS-CoV-2 has provided pipelines that could be readily modified, if needed, to produce vaccines tailored to stop new variants. The availability of multiple effective SARS-CoV-2 vaccines also provides society with robust alternatives to deal with emerging complications.
The bad news is that the longer it takes us to control the pandemic, the more likely it is that SARS-CoV-2 infections raging in India or Brazil, or smoldering in pockets of the U.S., could breed truly dangerous new variants that re-ignite the pandemic by escaping current vaccine protections or causing higher death rates. This is a vital reason why we must pursue all available means to reduce if not eventually eradicate SARS-CoV-2 transmission. Achieving high levels of vaccination is the strongest means to achieve this, and new studies confirm that mask usage significantly slows COVID-19 spread, reducing infections and deaths. Continued reduction in SARS-CoV-2 spread by mask usage, distancing and other safety practices directly adds to the herd immunity effects of community vaccination to help protect everyone.
As with the UK variant, more competitive new SARS-CoV-2 variants that arise anywhere quickly spread everywhere. Thus, the pandemic will not end for anyone until it ends globally. Accordingly, the US and other nations must work together to bring high level COVID-19 outbreaks like those in India and Brazil under control, for everyone’s mutual safety.
In conclusion, tireless efforts by health care workers, researchers, the pharmaceutical industry and others have given society the critical vaccines and other tools needed to bring this devastating COVID-19 pandemic under control.
It remains for us all to work individually and jointly to apply these tools effectively, guided by increasingly clear, hard-won knowledge and the best interests of the entire country. Staff across all areas of the Morgridge Institute are working diligently to support these efforts and to build further knowledge that will stop future pandemics and address other major biomedical challenges and opportunities.
Paul Ahlquist is director of the Morgridge Institute’s John W. and Jeanne M. Rowe Center for Research in Virology, and a professor at the University of Wisconsin–Madison.