What to know about the COVID-19 vaccines

Last updated Dec. 31, 2020

As the number of COVID-19 cases continues to increase, you probably have a lot of questions about coronavirus vaccines. Are they safe? Can you still get infected with COVID-19 if you've been vaccinated? How soon will you be able to get a COVID-19 vaccine and get back to some semblance of a normal life? When can cancer patients get vaccinated?

Xổ số miền bắc thứ 4 hàng tuầnFor answers to these COVID-19 vaccine questions and more, we spoke with our chief medical executive , infectious diseases specialist and head of Internal Medicine , and infectious diseases and infection control specialist Elizabeth Frenzel, M.D.

Why are health care workers receiving the COVID-19 vaccines before patients?

Tereffe: As vaccine production ramps up, there will be a limited number of doses available.

Federal and state guidelines require that, as long as vaccine supply is limited, the vaccine must be available to health care workers first. MD Anderson’s initial vaccination clinics will safely and efficiently vaccinate health care workers caring for highly immune compromised patients, those with increased risk of occupational exposure, those that support patient care and others who meet eligibility.

When will MD Anderson offer the COVID-19 vaccines to patients?

Tereffe: People receiving treatments that weaken the immune system – such as chemotherapy for cancer – were not included in many of the COVID-19 vaccine clinical trials. Since there are limited data on the safety of the vaccines in cancer patients, MD Anderson is doing careful due diligence before issuing recommendations and offering the vaccine to our patients, many of whom are immune suppressed or receiving treatment for cancer. Once our recommendations for cancer patients are finalized, we will share that information directly with patients through MyChart, as well as on our website and social media channels. Your care team will be able to give you information so you can make an informed choice about vaccination.

We are also preparing vaccine distribution plans for our patients who are eligible and wish to receive the vaccine from us once we are able to offer it. Once these plans are finalized, we will share this information with patients and caregivers, and provide assistance with scheduling vaccination appointments.

Please know we continue to actively review all of the latest evidence on COVID-19 vaccines in order to make the best recommendations for our patients.

It’s important to continue taking precautions such as wearing a mask, maintaining social distancing and washing your hands frequently, even after you receive a COVID-19 vaccine. These precautions will be necessary until public health experts advise otherwise.

Will people who’ve recovered from COVID-19 be able to get vaccinated?

Frenzel: Xổ số miền bắc thứ 4 hàng tuầnSince reinfection is a possibility, vaccination is expected to provide added protection for those who’ve recovered from COVID-19. However, you should wait to get vaccinated until your symptoms of infection have resolved and you have completed the quarantine period recommended by the CDC. In addition, if you received monoclonal antibody therapy or convalescent plasma to treat your COVID-19 infecton, you should wait 90 days after receiving those treatments to be vaccinated.

After symptomatic infection, natural immunity appears to persist for at least 3 months. Therefore you could choose to defer vaccination for 90 days if you desire. If your infection was asymptomatic, it should not factor into your decision to be vaccinated since you may not have effective immunity.

How do the Pfizer and Moderna vaccines work?

Tweardy: Our cells use messenger RNA (mRNA) to produce the various proteins our bodies need to function. The Pfizer and Moderna vaccines both use an mRNA sequence that codes for the unique spike protein on the surface of the SARS-CoV-2 virus. Once a person receives the vaccine, their cells take up that mRNA sequence and produce the COVID-19 spike protein. Their immune system then detects those proteins as foreign and creates antibodies against them, which helps provide protection from future COVID-19 infections.

Currently, both of these vaccines require two doses given a few weeks apart to be effective.

What are the other types of coronavirus vaccines being developed?

Tweardy: There are three other types being developed that are in the lead. One involves deactivated virus. Another type uses a carrier virus (such as an adenovirus) containing the part of the coronavirus’ DNA that encodes the spike protein. And another type uses a single protein from the tip of the spikes that cover the coronavirus and allow it to bind to and infect human cells.

The type that uses deactivated virus is the most old-fashioned and the least sophisticated. It involves injecting people with virus that’s been inactivated (or made harmless) through heat or some other means. This causes a very broad immune response in the recipient, but not necessarily the one you want.

Xổ số miền bắc thứ 4 hàng tuầnThe carrier virus method targets the really important part of the virus — the protein spikes that stick up like little maces all over its surface — instead of the virus as a whole. It prompts the body to generate the spike protein itself. Once that happens, the immune system recognizes it as an invader and starts developing antibodies against it. So, when the real coronavirus comes along, these antibodies can shut it down. This is the strategy that most of the vaccine makers are pursuing right now. 

The last type of coronavirus vaccine involves injecting people with the spike protein itself, instead of pushing their bodies to generate it.

All three of these last approaches have been used successfully, based on the studies done so far. The last one is just not quite as far along in testing as the RNA and carrier approaches are.

What makes the RNA-approach so different from that of previous vaccines?

Tweardy: This is the first time this type of technology has ever been used for a vaccine. And the speed at which it is being developed is truly mind-boggling.

Xổ số miền bắc thứ 4 hàng tuầnRemember, this particular coronavirus was virtually unknown in November 2019. The actual syndrome caused by it was only first described in December 2019. A month later, scientists had isolated the virus and sequenced its genome. That’s something that used to take a full year or more. Two months later, we had the first COVID-19 vaccine candidates. Four months after that, some were already in Phase III clinical trials. And we’ll have a coronavirus vaccine available to health care workers in December 2020.

We’re living through a modern scientific miracle. Vaccines have not been developed at this speed before. Vaccine development usually takes 10 to 15 years after the identification of a new infectious disease. I’ve been working in infectious diseases for 40 years, and I never would’ve thought it was possible.

Could this same mRNA vaccination method be used again against future coronaviruses?

Tweardy: Absolutely. This strategy has the capacity to almost let us anticipateXổ số miền bắc thứ 4 hàng tuần the next strain of coronavirus so we can be prepared for it, kind of like we do now with the flu.

Xổ số miền bắc thứ 4 hàng tuầnWe could sequence the next coronavirus that’s identified as distinct and separate from this one in a month or less. Once we had that, we could insert the sequence of its spike protein into every step of the vaccine development pathway. That could get us another vaccine for testing within three months.

With this family of coronaviruses, that could potentially allow us to have a vaccine ready before the next one even becomes a pandemic. So theoretically, we could stop the next pandemic in its tracks.

Are the coronavirus vaccines safe?

Tweardy:Xổ số miền bắc thứ 4 hàng tuần Yes. I think anyone who gets a coronavirus vaccine that has received an Emergency Use Authorization (EUA) from the Food and Drug Administration (FDA) can have confidence that it will be safe, and that the benefits of being vaccinated will outweigh the risks. Otherwise, it wouldn’t receive an EUA. The FDA has been looking at this very carefully, and each vaccine has had to be tested on a lot of people to get authorized for emergency use.

COVID-19 is caused by a coronavirus similar to SARS and MERS, and researchers were able to build upon previous work creating vaccines for these diseases as they searched for a vaccine against COVID-19. mRNA has been studied for many years in relation to the study of infectious diseases and as an area of opportunity in cancer treatment.

COVID-19 is the third in a series of coronaviruses. After SARS and MERS, we understand the pathogenesis and early aspects of immunity and have learned from those experiences and taken that knowledge to target the weak spot of coronaviruses.

Even more closely watched than the efficacy of the vaccines in the clinical trials is the safety of the participants. For the FDA to consider an application for emergency authorization of a vaccine, more than half of the people enrolled must have been monitored for at least two months. Preliminary data shows the observed side effects are very similar to the flu vaccine, such as pain at the injection site and fatigue.

The FDA’s vaccine advisory committee comprises experts in medicine and research who meet to review the request for EUA of a vaccine, and these experts evaluate the safety and efficacy of the vaccines. Clinical trial participants will continue to be followed even after any EUAs are granted.

Is it safe to get a COVID-19 vaccine if you're pregnant or breastfeeding?

Frenzel: Safety data isn't yet available on vaccine-associated risks during pregnancy or the effects of COVID-19 vaccines on breastfed infants or on milk production/excretion. In breastfeeding women, mRNA vaccines are not thought to be a risk to the breastfed infant.

The Centers for Disease Control and Prevention (CDC) says pregnant women are at increased risk for severe illness should they get COVID-19, and their babies may be at risk for adverse outcomes like preterm birth. For these reasons, women who are pregnant should consult with their health care providers to evaluate their personal risk of contracting COVID-19 as they consider whether to undergo vaccination. The decision is yours and should be based on available safety information and thoughtful consideration of the risks versus benefits of vaccination.

Should I be concerned when I hear that an ongoing COVID-19 vaccine trial has been paused?

Tweardy:Xổ số miền bắc thứ 4 hàng tuần No. It’s fairly common for studies to be stopped temporarily. This gives researchers time to determine if any serious adverse events people experience are due to the vaccine or caused by something else.

Even during a pandemic, life goes on, so people can still become ill for any number of reasons. If researchers determine the adverse events are unrelated to a vaccine, then studies can be restarted. This has occurred in the case of two big COVID-19 vaccine trials; the pause was lifted and the trial restarted after a review by independent trial safety experts determined that the adverse event was unrelated to the vaccine.

How long will the coronavirus vaccines be effective?

Tweardy: We’d obviously love for it to give lifelong immunity against COVID-19, but that remains to be seen, as many people in the clinical trials are still in the follow-up period. We believe at least three months, if not six months or more. More data is coming and will guide us for future planning. If I had to guess, I would say it’s probably going to fall somewhere between influenza and the mumps, in terms of longevity of protection. It will probably be closer to the flu, because respiratory viruses don’t tend to lead to long-term immunity. 

What are the chances that a person who gets vaccinated can still get infected with COVID-19?

Tereffe: We know from the data so far that the Moderna and Pfizer vaccines confer about 95% effectiveness after the second dose – meaning there were a few people who still experienced a symptomatic COVID-19 infection after their full course of vaccination. Among those who did experience a symptomatic infection, the vaccine helped prevent serious symptoms and hospitalization. We don’t have meaningful data on asymptomatic infections in the trial groups. That means that we don’t know if vaccinated people could still carry the virus and transmit it to others, without having symptoms themselves.

Xổ số miền bắc thứ 4 hàng tuầnThese are very highly effective vaccines – for comparison, the flu vaccine we get is 50% to 70% effective and it still has a big impact each year. It will take some time, but widespread vaccination have a big impact on slowing the spread of COVID-19.

Related stories

• Insights from a COVID-19 vaccine clinical trial participant
• When will we achieve herd immunity? 
• What counts as COVID-19 exposure?

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