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.


Researchers around the world are sequencing new variants of Sars-CoV2 as they emerge, but while it may be possible to pinpoint changes in the virus it’s not known what those changes might portend. That’s according to Stuart Ray, an infectious disease expert at Johns Hopkins.

Ray: Here I am noting that delta lacks those changes in most of the sequences, so while we thought 501, 44 were super important, this virus continues to surprise us, and delta has other features. So what we thought was important before may not be important now, and I think this is important as we think about where the next variant might come from. They keep on coming out of left field and so we have to be humble about our ability to predict what’s going to be dominant six months from now if we’re designing a new antigen for a vaccine for instance.  :29

Ray says that current vaccines are holding their own against all important variants of Sars-CoV2, dramatically reducing both hospitalizations and deaths related to infection. At Johns Hopkins, I’m Elizabeth Tracey.


Alpha, Beta, Delta, and most recently Mu. Variants of Sars-CoV2 are constantly arising but only some of them reach the level where they are monitored. Stuart Ray, an infectious disease expert at Johns Hopkins, explains.

Ray: We see variants arising all the time. But occasionally a variant will have genetic features, that are features that have been associated with changes in variants that have become dominant. Those mutations of interest can qualify a variant as being a variant of interest. They become variants of concern when they spread enough to play a significant role in the epidemic. Some observations of increased transmissibility, partial evasion of immune responses and so that makes them variants of concern.  :29

The World Health Organization developed the naming convention for Sars-CoV2 variants based on the Greek alphabet, which was welcomed by many because it simplifies communications about which ones are spreading most easily in different parts of the world, and may also help in developing vaccines. At Johns Hopkins, I’m Elizabeth Tracey.


The spread of the delta variant of Covid-19 may have reached a plateau in the United States, the most recent data suggest. Many have pointed to unvaccinated people as the primary driver of this latest surge. Mark Sulkowski, an infectious disease expert at Johns Hopkins, says optimism early in the summer contributed.

Sulkowski: One of the other factors was this return to normal activity. A poll taken in June where one out of three Americans thought we had turned the corner and optimism was reaching a peak – 89% of people were optimistic about the coronavirus situation- as they called it in the poll. Domestic and international travel, just a resurgence of travel as well, so people were getting back to normal activities, we went to reductions in mask wearing requirements and things like that, which are now reversed.  :31

Sulkowski says knowing the range of factors that helped the virus spread are informative in controlling it as well as helping people reduce their own risk. At Johns Hopkins, I’m Elizabeth Tracey.

In person school days are here, with many involving masking, physical distancing, and testing for Covid infection. Jennifer Katzenstein, a child psychologist at Johns Hopkins, says parents might consider a daily check in with their child as part of the new routine.

Katzenstein: I’ve been starting to really allocate time each day where you really sit with your child and listen. And as parents that can be really hard because you want to ask all the questions about the day and you want to find out what’s been going on. But if we can start spending five or ten minutes each day sitting with our child, asking how the day went, and then not filling that silence with more words, but rather just sitting and listening, so that they can share with us how they’re feeling.  :26

Katzenstein says the rapid pace of change that’s going on right now with regard to requirements designed to reduce the risk of Covid infection for kids in school can add to the stress of adapting to in person classes. She advocates mindfulness for parents, too, as any stress their child is experiencing affects everyone in the family. At Johns Hopkins, I’m Elizabeth Tracey.


Shutdown and transition to virtual school was tough on everyone, and now returning to school in person for many is also providing challenges. Jennifer Katzenstein, a child psychologist at Johns Hopkins, says this is all normal.

Katzenstein: (Jennifer) There’s a range of emotions as kids return to school, especially after virtual school for the length of time that they’ve been in virtual school. One of those may be relief, returning to the school setting, returning to their social interactions. But there also may be anxiety and worry, about returning to school with the demands of the school day. What I’m seeing, especially for our middle schoolers, is more uncertainty and anxiety, especially now that they’re changing classes. So for some of the kids going back to school is a big jump developmentally that can be causing anxiety and stress.  :29

Katzenstein says parents should try to be aware both of their children’s emotions as well as their own as we all accustom ourselves to the new routine. She advises seeking help if any issues seem to be worsening or if parents are feeling overwhelmed. At Johns Hopkins, I’m Elizabeth Tracey.


Covid-19 infection can be frightening for anyone, and now that kids are back in school many parents are more worried than ever. Aaron Milstone, a pediatric infectious disease expert at Johns Hopkins, says if parents are worried about a child’s symptoms they should not hesitate to reach out.

Milstone: I know one of the common questions I get is about what should be that threshold for parents to seek attention and go to their doctor. And I always tell parents if you’re worried it’s always okay to check in with your doctor. I mean there’s no harm in calling, scheduling an appointment and getting checked out. This year when kids have symptoms it’s equally important to get tested, cause we really need to know if kids have COVID so we can appropriately keep them away from their family members and other students, to keep their community safe.  :26

Milstone reminds parents that they really know their own child best, so when parents feel concerned it’s worth following up. Early recognition and management of a worsening condition is more likely to resolve well. At Johns Hopkins, I’m Elizabeth Tracey.