Can I spread the virus? How long will I be immune? Infectious disease expert weighs in on what we do and do not know about the coronavirus vaccine

The first shipments of COVID-19 vaccines arrived in Texas on Dec. 14. (Courtesy Adobe Stock)
The first shipments of COVID-19 vaccines arrived in Texas on Dec. 14. (Courtesy Adobe Stock)

The first shipments of COVID-19 vaccines arrived in Texas on Dec. 14. (Courtesy Adobe Stock)

As almost 60,000 doses of the COVID-19 vaccine will come to the Greater Houston area the week of Dec. 14, officials, hospitals and local public health agencies are preparing to begin the distribution process.

Although the initial batch of vaccines is reserved for health care workers, residents and staff members in long-term care facilities, and other groups who are considered to be the most at risk of contracting the coronavirus, the vaccines are expected to become available to the general public in the coming months as well.

To bring the pandemic under control as quickly as possible, Dr. Jill Weatherhead, an infectious disease and tropical medicine expert with the Baylor College of Medicine in Houston, said it will be crucial for people to get vaccinated when the opportunity becomes available. Dr. Weatherhead spoke with Community Impact Newspaper on Dec. 14 on a number of vaccine-related subjects, including what the interim data means, the state of ongoing analysis and the outlook for 2021.

What is known now and what is still being studied

Clinical trials for the Pfizer vaccine, which is the vaccine being distributed in Texas as of Dec. 14, are still undergoing interim data analysis, which means that all patients have been enrolled, but the trials are not at an endpoint yet, Weatherhead said.

The three major vaccines going through clinical trials—those from Pfizer, Moderna and AstraZeneca—prevent symptomatic disease, which Weatherhead said is important because it will prevent people from getting sick and hospitals from being overwhelmed. The initial data for Pfizer and Moderna suggests that those vaccines will protect someone against developing symptomatic disease about 95% of the time, regardless of age, race or ethnicity, she said.

What trials have not determined yet is whether the vaccine will prevent a person from transmitting the virus to someone else, Weatherhead said.

"A person who is vaccinated, hopefully, will not get severely ill, but that doesn’t mean they can’t spread it to someone else," she said. "We just don’t have that data yet. That data is currently being evaluated."

Because of this, Weatherhead said, it will remain crucial for people who get vaccinated to follow the safety precautions that have been in place since the pandemic began, including wearing a mask, keeping six feet of distance from others and avoiding crowds.

Weatherhead stressed the safety of being vaccinated and dismissed the idea that there is danger in being among the first to be vaccinated at this point in the process. More than 40,000 people were vaccinated in Phase 3 of the Pfizer clinical trial, she said.

"The [researchers] have evaluated both the safety and efficacy of these vaccines," she said. "We will learn about asymptomatic transmission, the durability of immunity—how long the immune reaction lasts—[and] the very rare side effects as you increase the number of people, but none of these should, at this point, interfere with people jumping in and getting their vaccines. They’ve been tested, and they’ve been evaluated extensively."

Combating the spread

Even nine months into the pandemic in the U.S., little is still known about how long a person is immune after they are infected with COVID-19, Weatherhead said. Because of this, she said, waiting for herd immunity to develop through natural infection is not considered an acceptable route by infectious disease experts and public health officials. Doing so would result in millions of deaths and still would not providing any clear picture of how long immunity will last, she said.

The vaccine is the only real way to reach a point of herd immunity while also keeping people safe and healthy, Weatherhead said.

"The vaccine is really the only mechanism by which we can protect people from getting sick and we can get back to a more normal lifestyle faster," she said.

The goal of the vaccination process is to have the entire community eventually be vaccinated, Weatherhead said.

The development of herd immunity varies from one virus to another. For certain diseases, such as measles—wherein one infected person can spread the virus to 12-18 others in a susceptible population—herd immunity requires that about 90% of people in a community be immune.

The early data on COVID-19 suggests that somewhere around 70% of the population will have to be vaccinated for the pandemic to be controlled, Weatherhead said.

"As [vaccine] production ramps up, it’s going to be important that the general public gets these vaccines to protect everybody, to protect those that can’t get the vaccine or those who may not have developed the strongest immune response," she said. "It’s really going to be a community effort."

Distribution process and outlook for 2021

The process by which the vaccine will be rolled out in Texas involves getting it to the most vulnerable groups first, including people who are exposed to the virus more, such as health care workers, as well as those who are most at risk of developing severe disease, such as people over age 65 and people with underlying medical conditions.

The hope is for the majority of health care workers and long-term care staff and residents to be vaccinated in the next few months, at which point the general public will begin being vaccinated. Once more data is gathered, vaccines will then become available to children.

By the spring, Weatherhead said she expects several other vaccine options to start becoming available, including more traditional vaccines, such as the protein subunit vaccine. In most cases, which vaccine each person takes will be dictated by what is available in the community, Weatherhead said. Certain groups, such as pregnant women and those with underlying medical conditions, should follow recommendations from the U.S. Centers for Disease Control and Prevention.

When it comes to masks and social distancing, Weatherhead said it is difficult to put a timeline down as to when those measures will no longer be needed.

"This is something that has never been done before, and it’s going to be a moving target," she said. "Optimistically, we would hope that this rollout process is full [steam] ahead in the spring and summer [and that] by next fall, we [would] have some more return to normalcy. Maybe it will be quicker than that; maybe slower. That’s why it’s so critical that everybody gets on board and does their part and gets their vaccine if it’s been OK’d by their physician or health care provider."

By Shawn Arrajj
Shawn Arrajj serves as the editor of the Cy-Fair edition of Community Impact Newspaper where he covers the Cy-Fair and Jersey Village communities. He mainly writes about development, transportation and issues in Harris County.