By Faye Chiu, CNN

(CNN) -- There has been a worrisome trend emerging in recent weeks: Cases among younger people are rising. In Michigan, hospitalizations among people in their 30s have climbed by over 600%, and those in their 40s by 800%. Average daily cases for children have also risen by over 200%. In Massachusetts, the largest increase in Covid-19 infections has been in children and teens.

What accounts for these trends? We discuss with CNN Medical Analyst Dr. Leana Wen. Wen is an emergency physician and visiting professor of health policy and management at the George Washington University Milken Institute School of Public Health. She's also the author of the upcoming book "Lifelines: A Doctor's Journey in the Fight for Public Health."

CNN: Help us to make sense of these numbers. Is there a new strain that's affecting young people more? Or is it just that young people are out and about more than before?

Dr. Leana Wen: The disproportionate rise in cases among young people is probably due to a combination of factors. First is the fact that older people are increasingly vaccinated and therefore very well-protected against Covid-19. About 80% of all deaths have been from people over 65. In this age group, more than half are now fully vaccinated, and about 75% have received at least one dose of the vaccine. That the proportion of those getting hospitalized is shifting more toward young people is expected, and in fact, demonstrates that vaccinations are working.

Another likely reason for why more young people are getting infected is the B.1.1.7 variant. This is the variant that first originated from the United Kingdom and is quickly becoming dominant here in the US. Studies are showing that this strain is more transmissible — meaning that there's now a higher risk of acquiring coronavirus from activities that were previously thought to be pretty safe. In addition to causing more cases, the B.1.1.7 is now showing to be more virulent, too, meaning that it causes more severe disease and therefore is more likely to result in hospitalization and death.

Combine that with the fact that younger people are more mobile and engaging in more activities, and that's probably what's accounting for an increased proportion and numbers of cases in younger age groups.

CNN: What are the implications for school? Does this mean schools will have to close?

Wen: Not necessarily. There are numerous studies that have shown schools can be some of the safest places for children if mitigation measures are put into place — in particular, enforced mask wearing, but also things like keeping children in "pods" or cohorts, improved ventilation, and some degree of physical distancing. Getting teachers vaccinated also protects them and reduces their likelihood of carrying coronavirus. Additional measures like regular testing will help, too.

That said, schools will need to take into account that there are more transmissible variants, so even more of these mitigation measures must be implemented. Schools in the UK and Europe have had to close to contend with B.1.1.7. Schools will need to be particularly watchful for extracurricular activities — for example, in some places, it's after-school sports that have been shown to spread coronavirus. Having good contact tracing is very important to track down ... the source of the virus and to target interventions appropriately.

CNN: If it's younger age groups who are getting infected, should we be prioritizing them for vaccination?

Wen: Initially, it made sense to prioritize vaccinations for those who are older and with chronic illnesses — these are the people most likely to become severely ill. Prioritizing them helped to save lives and avoid overwhelming our hospitals. Vaccinations are proceeding rapidly, and President Biden is expected to announce imminently that states should open up eligibility by April 19 so that all people 16 and older will qualify to receive vaccines. So it's just a matter of weeks before everyone who wants a vaccine is going to be able to sign up to receive one.

All that said, I do agree with specifically increasing access to those most likely to contract coronavirus and to spread it, too. Vaccination efforts should aim to make getting the vaccine the easy and convenient choice. For example, a vaccination drive on college campuses will bring vaccines directly to people. Similarly, vaccines can be offered at workplaces, on a walk-in basis. These efforts to increase access and convenience will be really important, especially for younger people who have other priorities to tend to.

CNN: What should people do now to protect themselves, if there is a more contagious variant around?

Wen: The same precautions we've been advising all along still apply. The B.1.1.7 variant spreads through the respiratory route, just like the wild-type, or common, strains, so please continue to wear masks, keep physical distancing, and avoid indoor gatherings with people who are not in your household. Try to hold off on gathering with people indoors until after you're vaccinated. Once you're vaccinated, you can see other fully vaccinated people indoors, but until then, please see people outdoors, with physical distancing.

And please, get vaccinated as soon as you can. The vaccines that are authorized all appear to be very effective against the B.1.1.7 variant. Getting vaccinated will protect you from becoming ill from coronavirus, and it will also reduce the likelihood of your spreading it to others.

CNN: Are there particular precautions for children to be taking, since those under 16 cannot be vaccinated yet?

Wen: I'd make sure that children who are back in school follow specific precautions such as wearing masks and sticking to their cohort. Be just as careful in social, informal settings as in formal school settings. The weather is getting nicer so try to have playdates all outdoors, with kids wearing masks, instead of indoors.

Know that children tend to get much less sick than adults, but some children have become severely ill and, tragically, some have died from Covid-19.

Kids under 16 cannot be vaccinated yet, but [for] parents and those around the kids, getting vaccinated helps to protect them. The end is not that far away, and the summer will hopefully be much better in terms of infection level. So please continue to take precautions to protect your children and your family.