Health Newsfeed – Johns Hopkins Medicine Podcasts

Mu is just the latest Covid-19 variant that’s drawing the attention of many, with potentially worrisome mutations that may predict how infectious it might be.  Anna Durbin, an infectious disease expert at Johns Hopkins, says current vaccines should still provide pretty good protection against mu.

Durbin: We know that with mu the antibody responses are similar to beta. Meaning that the antibodies don’t work as well against mu just like they did not work as well against beta. That being said however, we know that people who were vaccinated, part of clinical trials in South Africa where the beta variant was spreading, efficacy against infection was lower, so about 65%, but the efficacy against severe disease and hospitalization was about 95%.   :29

Durbin says that while the best case is being able to avoid infection entirely, avoiding severe disease and staying out of the hospital are very good outcomes. At Johns Hopkins, I’m Elizabeth Tracey.

When enough people in certain geographic areas choose not to be vaccinated against viral diseases, outbreaks happen. We’ve been seeing this nationally with measles for years, and Covid-19 is no exception. Anna Durbin, an infectious disease expert at Johns Hopkins, explains.

Durbin: It’s all about who’s susceptible to infection. You can have in your state for instance 70% of adults vaccinated but you could have 90% of those adults in one place. When it burns through, when it gets transmitted through and it now longer has susceptible people to infect we see reduction in infections. Unfortunately then, delta came in which was more highly transmissible, so it was able to infect when alpha wasn’t. It was able to infect more people at a time than alpha.  :31

Durbin notes that because it isn’t possible to determine who’s vaccinated and who’s not, remaining vigilant is your best strategy. At Johns Hopkins, I’m Elizabeth Tracey.

The mu variant of Covid-19 is spreading, with new variants cropping up all the time. Anna Durbin, an infectious disease expert at Johns Hopkins, says although variants are concerning, the beauty of mRNA vaccines is the ease with which new ones can be created.

Durbin: They’ve already made variant specific mRNA vaccines. It’s really easy to do. As soon as you know the sequence you can redesign your RNA insert. The other thing that they’ll do in terms of how you license it, it’ll be looking at antibody response, so it’ll be immune bridging trials to show that the variant antibody titers are within statistically specific designed range of the other mRNA vaccines and then they’ll be good to go.  :31

Durbin says other strategies such as masking are also a good idea since as long as the virus keeps infecting people new variants will continue to emerge. At Johns Hopkins, I’m Elizabeth Tracey.

The best strategy to mitigate Covid-19 infection is still prevention with vaccines, but if you develop the disease, new oral medicines are poised to take their place in treatment. Mark Sulkowski, an infectious disease expert at Johns Hopkins, explains.

Sulkowski: There’s still I think a strong push for oral antivirals, both a protease inhibitor in development from Pfizer and a drug that acts on the polymerase, molnupiravir, that Merck is helping to develop. I think both of those hold promise for early treatment and prevention. And there is a an EUA for the Regeneron monoclonal for prevention. I think the challenge is just the rollout of that. You’re now talking about people who do not have Covid-19, and figuring out how we’ll administer that.  :30 

Sulkowski says Merck issued a press release describing its new medicine, but notes that no studies have been published on the drug yet, but he welcomes new options to manage Covid-19. At Johns Hopkins, I’m Elizabeth Tracey.

Many countries have or are in the midst of rolling out third doses or boosters against Covid-19, even as the World Health Organization decries the practice. Anna Durbin, an infectious disease expert at Johns Hopkins, says while such a strategy might keep some well, it’s not the way to stop the pandemic.

Durbin: If you want to stop the spread of delta, if you want to stop the emergence of new variants giving booster shots is not the way to do it. We have to get unvaccinated people vaccinated. I think unfortunately the discussion around booster shots has been a bit of a distraction and has moved the discussion away from what do we need to do to get unvaccinated people vaccinated. Will a booster help your immune system? Yes. Will it raise your antibody titers? Yes. Do you absolutely need it? Most people probably not.  :33

Durbin says those with special needs such as transplant recipients may need a third dose to produce any antibodies. At Johns Hopkins, I’m Elizabeth Tracey.

Many vaccines require more than one dose to be effective in preventing disease, and Covid-19 is no exception. That’s according to Jonathan Zenilman, an infectious disease expert at Johns Hopkins.

Zenilman: We do know that the boosts, actually at several different dosing levels, provide exponential increases in antibody levels. The framework is are these really boosters or is the true schedule of the vaccine something that should be 0,1, and six months, very similar to other vaccines that we use. And actually was the problem that because of the pandemic they really needed accelerated schedules?  :28

Zenilman says that as global criticism mounts against providing third doses on a routine basis when so many people haven’t had even one dose, it’s worth considering that the best protection against Covid-19 may very well be a three or more dose regimen. At Johns Hopkins, I’m Elizabeth Tracey.

Antibodies are proteins that circulate in the blood and act as first responders to viruses, hopefully warding off infection. Antibodies are produced either in response to immunization or natural infection, but whether they provide a useful measure of protection is unclear. That’s according to Stuart Ray, an infectious disease expert at Johns Hopkins.

Ray: There’s the formal question of whether the antibodies measure the thing that we’re trying to detect. The other is whether there’s a correlation that’s useful, and whether we can identify people at risk in a reliable way. Neutralizing antibody assays can measure something but we don’t know exactly where the threshold is for protection. We can try to make some inferences but even that estimate, with the best estimates we have, is imperfect. But both because we don’t exactly know what level and we’re only measuring one particular function, there’s lots of reasons why there’s uncertainty.  :29

Ray says attempts to use neutralizing antibody levels against Covid-19 are a case in point for this uncertainty. At Johns Hopkins, I’m Elizabeth Tracey.

The EU and many other high income countries are turning increasingly toward booster shots for Covid-19, at least for some groups of people. Mark Sulkowski, an infectious disease expert at Johns Hopkins, explains some of the data.

Sulkowski: Israel was a country was there was a high and early uptake in vaccine in nearly 80% of adults were vaccinated. The delta variant emerged and there was a high case rate and hospitalization rate among vaccinated individuals. That prompted a third dose for persons 60 or older greater than or equal to five months since full vaccination. On Med Archive is this report, suggesting the estimated what they called ‘booster protection’ for individuals who received a third dose. The end of this was in August so it wasn’t a long period of follow up time. And this study has generated a lot of controversy.  :35

Sulkowski says the controversy stems from the short follow up time and notes that much of the world’s population still doesn’t have a first dose even as others are now moving to third shots. At Johns Hopkins, I’m Elizabeth Tracey.

Studies conducted over the last several months are bearing fruit as Covid vaccines for children appear close to deployment. Emergency use authorizations are expected from the FDA soon, with many parents anxious to have their children immunized. Jonathan Zenilman, an infectious disease expert at Johns Hopkins, describes the process.

Zenilman: There’s two groups of kids. One is five to twelve and the other is six months to under five. The trials to look at kids did not look at efficacy, the FDA allows something called bridging, and what they needed to do was show safety and dose range. The major issue with kids has been fevers, and we’ve seen this with the adolescents too but it’s playing out in kids as well. They have really good immune systems and they react to these things. Fevers in kids occur but they tend to be easily controlled.  :31

Zenilman says over the counter medicines can help. At Johns Hopkins, I’m Elizabeth Tracey.

Shedding virus is the term used to describe the state of being infectious to others, and with Covid-19 there’s a lot about this state we still don’t know. Anna Durbin, an infectious disease expert at Johns Hopkins, says the picture is even more complicated when someone who is vaccinated becomes infected.

Durbin: This is viral load by PCR and we don’t know how much of it is infectious. So that’s my first caveat. We could be measuring dead virus or virus bound to antibody but by and large the more virus you have the more likely you are to transmit, the more likely you are to be symptomatic which can lead to cough and other things that also improve transmission. And generally it could be also that you harbor the virus longer so I think there are several different factors and included in that is behavioral.  :31

Durbin says it is known that people who’ve been vaccinated generally experience less severe cases of Covid-19 but that they can infect others, but how long that period lasts is still being investigated, so for now, masks and physical distancing remain good ideas. At Johns Hopkins, I’m Elizabeth Tracey.