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The arrival of vaccines earlier this year offered a glimmer of hope that the COVID-19 pandemic was nearing an end. But the emergence of the delta variant has dampened some of that optimism.

The Star Tribune solicited reader questions about this new phase of the pandemic. Pulitzer Prize-winning health reporters Glenn Howatt and Jeremy Olson discussed the answers in their third appearance on the Curious Minnesota podcast.

Below is a rough overview of their answers to reader questions. Listen to the audio for a more complete version.

Since vaccinated people can contract COVID, and more cases helps perpetuate new variants, is there a path out of this pandemic?

Vaccination is the best way to protect yourself and the general population. That is how we are going to put an end to the pandemic. Despite stories of vaccinated people contracting COVID, it is not very common. And those who are vaccinated are far less likely to get severe symptoms or die.

The virus is always mutating. Some variants are highly contagious. But there are many others we do not hear about, because they are not causing a problem.

How can we keep babies and children safe from the delta variant? Should they be masking?

Children younger than 12 are not currently eligible for any of the vaccines. Wearing masks is effective, but proper fit is also important.

It is not recommended that children under 2 years old wear a mask. In that case, the best strategy is to surround them with protection. Adults around them should be vaccinated and wear masks in high-risk places.

Children are far less likely to contract severe illness or die as a result of COVID. There have been only nine COVID deaths in Minnesota among people under the age of 25. But children are vectors that can transmit the virus to people who are more vulnerable.

I have had COVID, and I am trusting my antibodies to do their job. I have not received the vaccine. What about people like me that have had COVID? How do they do when exposed to delta?

Antibodies could provide some protection. But research has shown that the immunity developed from infection, known as "natural immunity," is less effective than immunity provided by the vaccines. And if different mutations of the virus emerge, the antibodies from a past infection may not be equipped to tackle the virus.

There are also unknowns about how long natural immunity lasts – a concept called "waning immunity." There is a presumption that it fades over a matter of months, but research on that isn't yet conclusive. Immunity in vaccinated people also wanes, which is why federal health officials are recommending booster shots that will begin in late September.

If I received the Johnson & Johnson vaccine, and need a booster shot, can I get one from a different manufacturer?

The federal government is recommending that people who received the Pfizer and Moderna vaccines get a booster shot after September 20. That is because there has been some data showing that the vaccines' effectiveness wanes over time.

We do not know whether a booster dose will be authorized for the Johnson & Johnson vaccine, since it was approved later and the studies into its effectiveness are ongoing. It is likely, however.

How do we reach herd immunity, and what if anything will reach it?

Typically herd immunity refers to a level of population that has immunity to prevent an epidemic or pandemic. This time, we're trying to work ourselves out of a pandemic. So no one really knows what the number would be.

You also have to consider geography. If 80% or 90% of Minnesotans are vaccinated, there are still going to be pockets of the state that are lower than that – and some that are higher. So that presents an opportunity for the virus to continue to spread. And to a certain extent, we're seeing that in Minnesota right now.

The state had a goal early on to reach 80% vaccination, with a presumption that this would result in some level of herd immunity (giving the virus too few places to go). But Dr. Gregory Poland with Mayo Clinic said recently he thinks that the high transmissibility of the delta variant could mean that even 95% coverage may not be enough. That may mean that the COVID virus, like seasonal influenza, is just something we're going to have to live with over time.

Is there a threshold where vaccine mandates will be removed? Or will we be living with them forever?

There are no statewide or federal vaccine mandates right now. There are at some universities, as well as some individual businesses and governments. But vaccine mandates aren't uncommon. As children, we receive all kinds of vaccines — for tetanus, mumps, measles and rubella.

So it's just an open question whether COVID is going to join that family, meaning we would be receiving vaccines against that into the future. Or, alternatively, whether it's going to go away.

How is Minnesota tracking breakthrough cases?

The state has a case tracking system called REDcap. With every new positive case, they open a file and collect information. They also have a database of all shots given in the state — including COVID shots. Every day, they get new reports of positive cases. So they look at all that data to determine how many fully vaccinated people have been infected.

There were fewer than 10,000 breakthrough cases as of late August, which amounts to less than 1% of the fully vaccinated population in Minnesota. Those cases include nearly 700 hospitalizations and 69 COVID deaths. Many of those hospitalizations are people who went to the hospital for other medical procedures and tested positive for COVID during routine screening.

We have a celebration of life (for someone who passed from Covid) planned on August 28. We anticipate 100 people at a park shelter. Are such gatherings safe given the surge?

Outdoor transmission risk is substantially lower than indoor risk, but it isn't zero. The Minnesota Department of Health recorded an increase in July of outbreaks at large group events — defined as three unrelated people at the same event becoming infected. There were outbreaks at 13 festivals or fairs, eight weddings and one funeral.

So it is a risk, but there are ways to lower the risk. Outdoors is better. Social distance, if possible. And you can ask people to wear masks. There are things you can do to make even those low risks get lower.