As anxiety mounts for people due their second vaccine in the weeklong whiteout, experts reassure the public they have at least six weeks.

“Extending it to a six-week interval between the first and the second dose is OK,” infectious disease physician Manoj Jain said Thursday, Feb. 18.

The United Kingdom, and others using the two-dose AstraZeneca vaccine, which is not approved in the United States, have administered doses 12 weeks apart.

In late January, the Centers for Disease Control and Prevention approved the six-week interval between doses.

“This has been true about vaccines forever: You can get the second dose days, weeks after the actual dates of the scheduled doses,” said Dr. Rebecca Wurtz, assistant professor in the University of Minnesota’s College of Public Health.

The Shelby County Health Department is rescheduling the thousands of appointments missed this week to the same time, day and location next week. Appointments already made for next week before the winter weather canceled shots this week will be rebooked.

Both Moderna and Pfizer-BioNTech vaccines are 95% effective after two doses. And while few people recommend it, the vaccines do offer some protection at only one dose.

Pfizer’s is about 50% effective in 10 to 12 days after the first injection; Moderna is 80% effective after the first dose.

For people who are beyond the six-week interval, the CDC does not recommend starting over with the first shot, Jain said.

“If people are concerned, their physician can have blood drawn to check for antibodies,” he said. “That will give us an excellent perspective on whether you have antibody protection or not.”

Jain suspects one dose would be enough to protect against the kind of serious illness that requires a hospital stay.

“The problem is that we haven’t had clinical trials that take people and give them an interval of three months or four months or five months. We just haven’t had the time or the ability to have a wider gap between the two doses,” he said.

Jain said he has “high hopes” for the pending Johnson & Johnson vaccine, which is shown to have efficacy of 60%-70% against mild cases and 90% effective against severe cases.

Experts hope it will be approved for emergency use in the U.S. late this month or early March.

The positives are that it requires only one dose and can be kept in a normal refrigerator, which will ease supply-chain burdens for administering the vaccine in remote areas in the U.S. and abroad.

Vaccines are not scheduled to be given in Shelby County in mass doses until next week, which means this week has been nearly a total loss for ramping up vaccination numbers.

“But soon enough, we should be able to catch up in getting all the vaccines in arms,” Jain said.

The limiting factor has been the supply of vaccine. The state Health Department has already predicted weather will slow some deliveries for next week.

“I am convinced that in the next month or two, all of this is going to flip and our vaccine supply is going to be abundant, but the demand will not be sufficient,” Jain said.

When weather permits, vaccines are being administered in Shelby County at four mass sites, the Pipkin Building, Germantown Baptist Church, Appling City Cove and Southwest Tennessee Community College in Whitehaven. It is also being delivered two days a week on a smaller scale at the commodities warehouse on South Belvedere.

Next week, a fifth mass center is scheduled to open at Greater Imani Cathedral of Faith, 3824 Austin Peay in Raleigh.