What happened

The coronavirus pandemic is still very much with us, and coronavirus stocks Pfizer (PFE -3.85%) and Moderna (MRNA -2.45%) remain on the radar of many investors.

Some good news for the two companies' COVID-19 vaccines pushed Pfizer stock more than 3% higher on Tuesday, beating even the 2.5% gain of a surging S&P 500 index. Moderna also gained, but at a more modest 1.5% rate.

So what

On Friday, as expected, the Food and Drug Administration (FDA) amended the Emergency Use Authorizations of Pfizer's Comirnaty and Moderna's mRNA-1273 (also known as Spikevax) to include very young children. The former (developed in partnership with German biotech BioNTech) has been given the green light for youths from 6 months to 4 years old, and the latter's age range is 6 months to 5 years.

The FDA's move didn't come as a great surprise, particularly following a unanimous recommendation from members of the regulator's vaccine advisory panel last Wednesday. 

Then on Saturday the Centers for Disease Control and Prevention (CDC) formally recommended that all individuals in that age group be administered one of the two vaccines. This includes children who have already had, and recovered from, COVID-19.

Now what

There are an estimated 20 million children in the U.S., so the high demand for both Spikevax and Comirnaty should be sustained. 

Meanwhile, on Monday Pfizer and peer Valneva announced that they have entered into an equity subscription agreement. Under the terms of the deal, Pfizer is to invest 90.5 million euros ($95 million) in the France-based biotech; this represents a stake of just over 8% in Valneva.

With those proceeds, the two companies said Valneva would advance the development of the Lyme disease vaccine candidate VLA15 they are partnering on.