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Dispelling fear and uncertainty surrounding the Delta variant

Mark Parker



Dr. John Greene is Chair of the Infectious Diseases program at Moffitt Cancer Center. He believes the days of widespread Covid outbreaks resulting in mass hospitalizations and deaths are over Photo: Screengrab.

Just as many questions and myths were circulating the original form of Covid-19 almost a year and a half ago, the mutation known as the Delta variant has brought new fear and uncertainty.

Dr. John Greene, Chair of the Infectious Diseases program with Moffit Cancer Center, recently sought to answer some questions and dispel some myths about this highly contagious form of Covid as it rapidly spreads through the Tampa Bay area and the state of Florida.

Greene said that the Delta variant is around 60% more transmissible than the original, although the good news is that it has not proven to be more virulent – meaning the effects are not more severe. Delta is now the most common strain by a wide margin, 83% of all Covid-19 infections.

While Greene compares the contagion level of Delta to that of chickenpox, he also thinks there are multiple reasons why more people are not getting severely ill and dying. One is that some could have partial immunity due to previous exposures. Another is that there are now proven treatments such as monoclonal antibodies given to the most vulnerable to keep them from getting sick enough to die.

“I don’t think the mortality will be as bad,” said Greene. “Although the hospitals are full, including the I.C.U.s.”

Many people are worried that vaccines will not protect them. While it is true that all three vaccines currently in use are less effective versus the Delta variant, they still greatly increase the odds that a person will not contract the virus. Greene said that Pfizer is 95% effective against the original variant and is about 88% protective against Delta after the second dose. Moderna’s vaccine is thought to be about 72%, and Johnson and Johnson’s have shown to be the least effective -though still around 65% to 70% protective against the illness.

Greene said that while there is still a chance of vaccinated people contracting the virus, it is usually mild compared to the unvaccinated.

“A lot of people can still get a mild illness, so the vaccine is preventing them from being hospitalized,” said Greene. “The unvaccinated are the ones who are bearing the brunt of the Delta variant.”

Although a vaccinated person who is infected carries about the same viral load as an unvaccinated person would, the period of contagion is reduced from 7-10 days to 3-5 days. Not only is the period of contagion shorter, but the onset of illness is also delayed, added Greene.

While Florida has been setting pandemic records for its number of cases and hospitalizations recently, Greene said that the state is “sort of in the middle compared to the other states” when it comes to the percent of the population that is vaccinated. According to, Florida is about 49% fully vaccinated, with Hillsborough County at 44% and Pinellas County at 51%.

In response to people who are worried about vaccine side effects, Greene said that the chances of being hospitalized, put on a ventilator, and even death related from Covid are significantly higher than having an adverse reaction to a vaccine. Hospitals are now seeing a greater influx of patients in the 20-year-old to 40-year-old age range, which he attributes to that group being the most reluctant to receive the vaccine.

“The reality is that you need to get vaccinated because you could become severely ill and deal with the prolonged Covid-19 symptoms, where some people can feel very ill or tired for six months or more,” said Greene.

Greene said there is an upcoming meeting between Pfizer, the Centers for Disease Control, U.S. Food and Drug Administration and the vaccination boards in which a vaccine booster may be recommended. Greene said that if someone is immune suppressed and does not make enough antibodies, a third booster could get them to a high enough level to prevent infection – including the Delta variant. 

“I would get the booster right now because I want my titer (concentration of antibodies) to be as high as possible to prevent infection,” said Greene. “When all the data is in, they will probably come out with a recommendation similar to the flu – where every year you will get a vaccine. I believe that is where we are headed.”

Another point of debate is whether those who have already contracted Covid should still get vaccinated. Greene said they should, with the logic being that a person’s antibody titers may not last as long as the vaccination would and may not be high enough to prevent variants – such as Delta.

“Even if you have been infected, you should get the vaccine to boost your titer so you can have the best immunity to prevent any variant,” said Greene.




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    Karen J Douglas

    August 3, 2021at3:54 pm

    Have been trying to get data/information on the booster. I got double vaccinated in Feb of this year. (Pfizer) Well, it’s 6 months old now……when/where can I get the booster? 72 years old.

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