You probably don’t think about sewage much but worldwide, many public health experts are increasingly turning to monitoring the stuff for infectious diseases, especially viruses. Stuart Ray, an infectious disease expert at Johns Hopkins, says this has been one of the lessons of the Covid-19 pandemic.

Ray: Sewage can be so valuable to us in epidemics, and I think it also underscores our learnings that we need for Covid, because this virus probably does infect the gut but maybe isn’t transmissible that way but it does leave a signature in sewage and so we can use that as a tool. So I think that we’re going to do more surveillance, and the power of molecular biology for all the things it’s doing for us. For managing cancer, for diagnosing all these things and so this is another example of molecular biology really changing the way we manage risk.  :30

Ray notes that the worldwide recognition of monkeypox is also being monitored in this way, and predicts that sewage surveillance will become standard practice going forward, helping in early recognition efforts of emerging infectious disease outbreaks and novel pathogens. At Johns Hopkins, I’m Elizabeth Tracey. 


As Covid infection continues apace, we have seen dramatic declines in flu and shifted patterns of other viruses, such as respiratory syncytial virus or RSV. Stuart Ray, an infectious disease expert at Johns Hopkins, attributes such changes to human behavior.

Ray: From a temperate zone life we think of flu as a winter virus, but in the tropics, the hot muggy times can be the peak of the flu season. So viruses don’t look at the calendar, but peoples’ behavior changes over time, and so there are a lot of dynamics that we ascribe to viruses, which are human behavioral dynamics. We saw that with the surges, that a lot of the surges couldn’t be explained by the seasons, they were explained in part by people getting relaxed and then the exponential growth of an infectious disease. We now have some learnings that we might be able to use to disrupt those patterns.  :34

Ray specifically notes that becoming more aware of when respiratory viruses of all types are increasing in transmission would also identify when wearing a mask might help. At Johns Hopkins, I’m Elizabeth Tracey.


 Masking reduces transmission of respiratory viruses like Covid-19 dramatically, yet naysayers abound. Stuart Ray, an infectious disease expert at Johns Hopkins, says one way to possibly overcome their objections is to provide an opportunity to really see what’s out there.

Ray: Leadership has not done a good job of helping people explore masks to find one that fits them well. Many people who have the means to try out masks haven’t done it but many people don’t have the resources and we really should be providing a wide range of masks to people and good education about how to know whether it fits well. In the hospital we do fit testing where we spray an aerosol, and we can tell whether or not the aerosol gets through the mask. Why don’t we have that in drugstores? And give people the chance to test a bunch of masks and find one that fits?  :30

Ray says other respiratory viruses such as the flu are also very effectively blocked by a properly fitted mask, and we could consider broadcasting public health alerts when viral transmission is high so people could choose to wear a mask then. At Johns Hopkins, I’m Elizabeth Tracey.


How did wearing a mask to prevent infection with a respiratory virus become so political? Infectious disease expert Stuart Ray at Johns Hopkins says he doesn’t know the answer to that, but thinks time will allow many of us to take a broader view of what we may still need to do to protect ourselves and others from Covid-19.

Ray: The current situation is that we have people who don’t yet have distance on it I think. People are still feeling very emotional about mask wearing, about other behaviors. So this is still a fraught time in dealing with this. Fortunately we have the tools now for people to keep themselves and their loved ones safe. Preventing transmission is a way of caring for others. I do think that people generally want to do well for the most vulnerable if they’re reminded, but sometimes we need to be reminded, and that you can’t look at someone and tell if they’re vulnerable.  :31

Ray says people who are immunocompromised and those with certain chronic health conditions may not look unwell but remain at high risk for Covid infection. At Johns Hopkins, I’m Elizabeth Tracey.


Are you still wearing a mask? Keeping your distance from others or avoiding crowds? Rates of Covid infection remain high, and hospitalizations and deaths are more or less steady. Stuart Ray, an infectious disease expert at Johns Hopkins, says although practices vary around the country, some take home messages seem clear.

Ray: The range is dramatic, and I think that we’ve learned a lot, and as the data percolate through, and we really have a chance to have a little distance on all this and look back, I think we’ll recognize that there were some things that really did keep us safer. Evidence from our experience at Johns Hopkins Hospital is that masks work amazingly well. The worn mask that’s fitted well, that’s worn, so you find one that’s comfortable really does provide a dramatic degree of protection and we saw very little transmission in healthcare workers who were wearing a mask.  :30

Ray says it’s premature to declare Covid infection on the decline, noting that with the arrival of fall emergence of new variants is likely. At Johns Hopkins, I’m Elizabeth Tracey.


Covid vaccines have been authorized by the FDA for young children, and Novavax is poised for review and authorization by the agency. Do we really need these new measures in our quest to control Covid-19? Stuart Ray, an infectious disease expert at Johns Hopkins, says yes.

Ray: Having all these vaccines is exciting because we need options. Some people live in a remote place where refrigeration is not easy and so having a vaccine like Novavax that’s stable for longer periods of time at more reasonable temperatures means that we can get vaccine to more people. It also provides us another option in people who might be at risk for some of the rare complications of the mRNA vaccines and the adenovirus based vaccine. As we go forward and learn, we may learn the right schedule, the right sequence of events, the right selections among these.   :30

Ray notes that vaccines are a bright light in the pandemic story, having likely saved the lives of millions of people so far. At Johns Hopkins, I’m Elizabeth Tracey.


Covid-19 has revolutionized many things, including how antibodies to fight the infection are developed. Stuart Ray, an infectious disease expert at Johns Hopkins, explains.

Ray: There’s some really exciting technologies here. An antibody has two major features, it’s shaped like a Y. The tips of the Y bind the virus and then the tail of it people often kind of ignore but it actually has all of the machinery for the body’s management of that antibody. With engineering of that tail, they’ve been able to make antibodies that can stay in the circulation for three to six months so we may see opportunities to protect people giving monoclonal antibodies that last a long time, can provide a layer of protection that we can’t provide through vaccination.  :32

Ray emphasizes that these long lasting antibodies may be especially helpful in people who are immunocompromised, such as transplant recipients or those undergoing certain types of cancer treatment. At Johns Hopkins, I’m Elizabeth Tracey.