Frederick Southwick’s, M.D., first encounter with a coronavirus was in 2003. The virus, SARS-CoV-1, caused a respiratory illness, which was known clinically as “SARS” and had a 13% mortality rate that ended up infecting over 8,000 people from 30 countries.
Before the virus arrived in the United States, Southwick, a member of the UF Emerging Pathogens Institute and a UF College of Medicine professor, was tasked with looking into SARS-CoV-1. Although the virus had a relatively high mortality rate, Southwick found that it was, fortunately, not very contagious. Simple public health measures like testing people with symptoms, isolating infected patients and restricting travel helped bring the outbreak under control. The disease caused by SARS-CoV-1 ultimately resulted in over 900 deaths worldwide before it finally burned out in 2004, and the United States ultimately saw only a few dozen cases.
When the virus that causes COVID-19, SARS-CoV-2, first appeared in 2019, Southwick recognized the new coronavirus as a more contagious version of SARS-CoV-1. Although he saw that the new disease had a lower mortality rate, he still worried about what would happen if the disease spread.
“We said whoa, this guy looks like it causes a similar severity of disease but it’s much more contagious,” Southwick recalled. “This is really bad news.”
Southwick’s concerns ultimately came true as COVID-19 took the world by storm.
From the beginning, the COVID-19 pandemic was plagued by myths. The most significant misunderstanding about SARS-CoV-2 was how it spread—the World Health Organization originally said it spread through surfaces, not the air. Scientists would later say this error played a major role in allowing COVID-19 to spread as far and wide as it did.
At the time, papers showed that the virus survived and could be transmitted on surfaces—but these studies were done by polymerase chain reaction rather than cultures. PCR can amplify small segments of DNA, creating millions or billions of copies of a fragment in just a few hours. It can also be used to detect RNA viruses like SARS-CoV-2, with an added step where an enzyme first converts single-stranded RNA to DNA.
Because PCR is so sensitive, it’s useful in diagnosing patients who may have been infected by a slow-growing pathogen or who are in the early stages of infection with low, hard to detect levels of a virus. But in testing surfaces, this could lead to a strong positive result even if a surface had only trace amounts—not enough to infect someone—or had picked up genetic material from viruses that were dead and no longer infectious.
“I remember after my wife and I went to the grocery store we would clean everything off. Everybody was paranoid about surface contamination and we were very scared, but it turned out that was completely wrong,” Southwick said.
Over time, people began to realize that the main way the virus spread was through aerosol particles—one person’s speaking could generate enough virus-laden droplets to infect other people. Led by EPI member John Lednicky, Ph.D, the EPI played a key role in the research. The team’s work demonstrated the importance of aerosol transmission of the virus, making use of sophisticated instruments that allowed scientists to culture the virus from the air. Interestingly, the WHO has recently come out with a new position paper that supports the importance of aerosol transmission in COVID-19, as well as other respiratory infections.
“Initially, the CDC mistakenly said that you only need to wear a mask if you’re working in the hospital taking care of a patient with SARS-CoV-2. But in reality, everybody should have been wearing masks from the start,” Southwick said.
Confusion about the six-foot rule
Even after catching on to the dangers of airborne transmission, the world was still paying attention to the wrong thing, Southwick said. The Centers for Disease Control and Prevention recommended that people practice social distancing and keep at least six feet apart from others to avoid inhaling droplets from people who may be sick.
But this rule was born of a misunderstanding, said Lednicky, a professor at UF’s College of Public Health and Health Professions Department of Environmental and Global Health. When we exhale, cough, sneeze or talk, we release droplets from our nose and mouth. Some of the droplets are visible, but others are too fine to see with the naked eye. The six-foot rule was created with the idea that big droplets carrying the virus would fall to the ground before they could reach other people. But these were never the biggest threat—the real danger came from fine aerosol particles, which stay airborne long after the person who expelled them has left the room.
“Big droplets fall near you, but the small ones stay in the air. And for bacteria that might be important because they will live for a long time on a surface,” Lednicky said. “But for a respiratory virus, you can wash your hands all you want—if it’s in the air, you’re still in trouble.”
The six-foot rule helped to slightly reduce the risk of transmission in large spaces. In smaller spaces, though, an entire room could quickly fill with aerosol particles. People might still be safe if the space had frequent air turnover, but older buildings without proper ventilation could be especially dangerous.
More people started wearing masks once they realized COVID-19 was primarily transmitted through the air, Southwick said. But many masks didn’t effectively filter out tiny aerosol particles because they weren’t woven finely enough, in the case of cloth masks, or because they gaped at the sides, in the case of common surgical masks. Southwick added that N95 masks, which form a tight seal around the nose and mouth, were the safest.
“If we had responded in a proper manner, we could have slowed transmission and potentially contained this virus before it got really bad,” Lednicky said. “But there were a lot of people moving around very quickly. This gave the virus ample opportunity to spread around the world.”
New COVID variants, new sources of confusion
The more SARS-CoV-2 spread, the more chances it had to mutate and sprout new variants of COVID-19. These variants differed in severity of disease, symptoms they produced and how easily they could be transmitted.
The Delta variant of the virus, arguably one of the more famous variants, arrived in the spring of 2021. Studies showed that it came with a higher risk of severe disease and hospitalizations in unvaccinated people than other variants.
Later that same year, in November, the Omicron variant overtook Delta as the dominant variant. It proved highly transmissible, but evidence at the time suggested that the Omicron variant came with milder symptoms and a lower mortality rate.
“We kept having these waves of new variants, and when Omicron came, the word on the street was that it’s milder,” Southwick said. “And we were in the hospitals, so we wanted to know if that was really the case.”
Southwick argued that previous studies showing Omicron as a milder variant failed to account for differences between healthcare providers and their facilities. So, he and his team designed a study that would compare only Delta and Omicron cases being treated at the Hospitalist Service at the University of Florida Shands Hospital. This gave them maximum control over variables that other studies struggled with, such as differences in staff expertise, varying criteria for patient admission and disparate treatment timelines.
In the end, Southwick’s team found that the Omicron variant did tend to cause a milder infection but had a comparable mortality rate to that of the Delta variant.
“When we looked at who got the Omicron infection and ended up in the hospital, it was primarily people over 65 with underlying diseases, instead of young people. So, while overall the severity of infection was reduced in the general population, it remained a dangerous infection in the elderly and immune compromised; among these groups, there was still a need to take precautions when the disease was circulating in the community,” Southwick said.
Understanding the differences between variants can help doctors treat patients more effectively and public health resources can distribute more efficiently. To that end, Southwick recommended adopting a more holistic approach in studying variants and considering who is getting infected.
Why we still haven’t figured out long COVID
Over four years after SARS-CoV-2 was first identified, many people are now grappling with long COVID. The WHO defines the condition as cases where symptoms have either persisted or new symptoms developed three months after the initial COVID-19 infection. It often affects the brain, causing difficulty concentrating and memory loss, but it can also affect any other part of the body including the heart, lungs, kidneys and skin.
According to Lednicky these are only guidelines though, as long COVID has proven incredibly difficult to study.
“We only have a vague sense of what it is. What we know is that there is such a thing as long COVID and people are genuinely suffering,” Lednicky said. “At a bare minimum, we can usually say long COVID is the lingering of symptoms that may occur after someone has COVID.”
Long COVID manifests differently in different people and follows varying timelines, making it nearly impossible to make any kind of blanket statement about the condition.
To further complicate the matter, latent infections may get reactivated in patients. Long COVID cases also often come with co-infections from pathogens like Epstein-Barr Virus and the Human Immunodeficiency Virus 1.
These different cocktails of pathogens only add to the variations in disease progression that already exist due to differences in patients’ age, body weight and gender. When all is said and done, one person’s long COVID may have little in common with someone else’s long COVID.
COVID vaccines work, and we still need them
When the State of Florida released COVID-19 vaccines to all residents 16 years and older in April 2021, UF had to confront the logistical feat of vaccinating over 52,000 newly eligible students.
To get it done, Southwick worked with the EPI’s Deputy Director Michael Lauzardo, M.D., who oversaw UF’s mass-vaccination efforts. They worked with a team to set up a 32,000 square foot space at Ben Hill Griffin Stadium with workstations where vaccinees could check in, fill out the consent form and get vaccinated.
Southwick suggested ways to streamline the workflow by laying out the room to reduce idle time and setting expectations for how long it took to get everything done. He and his team monitored the time closely for each of the stations, and they found certain people were taking much longer because they were having extended conversations with patients.
“We told them they can’t do that,” Southwick said. “You know, we want to give a vaccine every one and a half minutes. You really had to set up expectations for behavior and time, then keep track of that. Once we did that, we got the high efficiency that we needed.”
Southwick, Lauzardo and others who helped plan the mass COVID-19 vaccination site were able to vaccinate over 5,000 people in a single 10-hour day. The team published their approach and takeaways so others could learn from their experience.
Once the vaccine was available, Southwick said, it became a critical tool for slowing the spread and reducing the mortality of COVID-19. While we’ve come a long way in understanding COVID-19, some myths still prevail and contribute to hospitalizations and deaths that could be avoided.
Southwick said doubt about the COVID-19 vaccine – even though scientists and reputable public health agencies have shared evidence showing it is both effective and safe – is the most significant COVID myth that still persists.
“During the Delta peak, Florida dropped in vaccination rates even though we had plenty of vaccines,” Southwick said. “It’s estimated that there were 16,000 lives lost because of the lack of vaccinations in Florida during that period. A lot of the people that died were young, and it was preventable too.”
Southwick’s greatest hope at this stage in the pandemic is that people will continue to get COVID-19 booster shots. Since the virus has adapted to become more effective at spreading from person to person, the disease itself has gotten less severe. But every week in the United States, COVID-19 still causes thousands of hospitalizations and hundreds of deaths. For these reasons, Southwick says COVID-19 vaccines and booster remain critical public health tools.
Written by: Jiayu Liang