(CNN) Many millions of Americans are now vaccinated and itching to get on with something resembling their pre-pandemic lives, but new Covid strains are afflicting younger people who have had less access to vaccines and are less likely to maintain social distance.
The Biden administration announced Tuesday its goal of opening vaccine eligibility to all Americans over the age of 16 by April 19. It also made clear it would not create a federal "vaccine passport" or require vaccines for travelers or businesses.
"The government is not now, nor will we be, supporting a system that requires Americans to carry a credential. There will be no federal vaccinations database and no federal mandate requiring everyone to obtain a single vaccination credential," White House press secretary Jen Psaki told reporters.
The next question for many Americans is how to make sure the person nearby -- on a plane, in a restaurant, at school -- has been vaccinated against Covid.
The two emerging schools of thought are:
The governors of Texas and Florida have both signed executive orders banning so-called "vaccine passports" or any kind of requirement by local governments or businesses.
Florida Republican Gov. Ron DeSantis last week banned local governments from issuing any kind of vaccine passport and banned business from requiring any such form to provide services.
He cited personal freedom and said such passports would "create two classes of citizens based on vaccinations."
Texas Republican Gov. Greg Abbott followed suit with his own order, which forbids Texas agencies from requiring a vaccine for any service.
"Government should not require any Texan to show proof of vaccination and reveal private health information just to go about their daily lives," he said in a video posted on Twitter.
The Biden administration has worked with nonprofits and tech firms to develop a set of standards for people to prove they've gotten the vaccine, according to at least two administration officials.
Airlines and cruise ships have all considered some form of vaccine verification.
It would be especially important to the cruise industry, which has deep ties to Florida. Norwegian Cruise Line Holdings, for instance, submitted a plan to the US Centers for Disease Control and Prevention on Monday that plans a return to operations from US ports in July.
The plan envisions a requirement that crew and guests be vaccinated: "We believe that through a combination of 100% mandatory vaccinations for guests and crew and science-backed public health measures ... we can create a safe, 'bubble-like' environment for guests and crew. We look forward to joining the rest of the travel, tourism and hospitality sectors in participating in this next phase of our recovery."
A vaccine requirement for domestic travel seems unlikely but very possible for international travel, especially if countries that currently require quarantines for travelers switch to requiring vaccines.
International airlines are expecting that a vaccine passport could help open up travel again.
"In the short term, yes, I think that the vaccine passport will be helpful to give confidence both to governments and to the passengers in our industry to start travelling again," Qatar Airways Group CEO Akbar Al Baker told CNBC's Hadley Gamble on Tuesday.
Companies have already been working on apps that allow users to upload information about their vaccines or Covid tests and then scan QR codes for admittance to flights or concert venues.
The UK is similarly testing Covid vaccine certifications for residents who want to enter soccer matches and other large gatherings, but will not require them to enter essential shops or public transportation. Israel already has a "green pass" that allows holders to go to concerts or the theater.
There's a big difference between asking for something and requiring it. And there's a difference between a company requiring something in exchange for its service and a government entity requiring it.
Companies and stores in Texas and Florida still require masks, for instance.
But there is also an anti-authority streak in this country, which is why the US has no federal gun registry. That the government should not be trusted with certain information is not up for debate.
In a pandemic with an economy trying to emerge, however, the interest of public safety should also be considered, especially where it comes specifically to masks and vaccines.
Look at the mask-free photos from the sold-out Texas Rangers home opener. Or look at the images of spring breakers on Florida beaches. Florida has seen more cases of the dangerous B.1.17 Covid variant than any other state, according to the CDC. Vaccines appear to protect against it.
Kids attending school must get numerous shots, depending on the state, in order to receive an in-person public education. But vaccine hesitancy even for long-used inoculations against polio and other diseases has been an issue in US classrooms.
It is not clear when kids under 16 will be eligible to receive the Covid vaccines, much less when school districts or states will require them. Plus, the Covid vaccine is only authorized for emergency use, not fully authorized. That's why members of the armed forces have the option of getting it, rather than the battery of vaccines they're required to have.
Privacy is a real issue. There are very real concerns, particularly if there were to be a list maintained by a government entity. The American Civil Liberties Union has cautioned about privacy dangers from any sort of vaccine passport and wrote a list of its guidelines for a vaccine passport system:
The European vaccine passport. The European Commission unveiled its proposal for a European Union "Digital Green Certificate" in March. No exact end date was given for the certificates, with the commission saying they will be suspended once the World Health Organization declares the end of the international public health emergency caused by Covid-19.
But EU data protection bodies issued their own warnings on Tuesday, advising against extending the use of vaccine passports beyond the current pandemic and warning they could pose "risks to the fundamental rights of EU citizens."
The agencies also raised concerns over the prospect of a "de facto requirement" for people to present vaccine passports to enter shops, restaurants, clubs, places of worship and gyms, as "has already been suggested."
"Trust, but verify," is the contradictory old Russian proverb that President Ronald Reagan applied to the Russians he didn't trust to make good on promises of nuclear disarmament.
It's being scrambled by today's politics of vaccines, where there's a growing effort to ban a verification process, and voting rights, where pushes for more stringent voter ID rules are being pushed.
Vaccinate, don't verify. Republican governors, having bucked the science to outlaw mask requirements in their states, are trying to get ahead of the next step in Covid protection and ban anything that resembles vaccine passports.
Verify, then vote. The same governors, we should note, are pushing to put obstacles between voters and the polls to ward off the potential for voter fraud there's no evidence occurs.
Alongside the Manhattan Project and the moon shot, you can place the Covid vaccine effort.
More than a third of Americans have gotten a dose of something that didn't exist a year ago. President Joe Biden brushed aside criticism that his vaccination targets have been too easily achievable during a stop at an Alexandria, Virginia, vaccine clinic Tuesday and later amped up the pace, saying all Americans who want a vaccine should be eligible to get one by April 19 and that 200 million shots should be in American arms by then.
There are real questions about whether vaccines have been distributed equitably, whether the government has done enough to get those hardest hit by the coronavirus on board and how to get the large portion of Americans who don't want the vaccine to get on board.
But give the vaccine effort this: It was begun under then-President Donald Trump and taken up by Biden, it's included the public sector working in league with the private sector, it's stretched from local pharmacies to massive vaccine sites. And it has brought the US closer every day to a return to normalcy.
Read this from CNN's Deidre McPhillips:
The United States is currently administering Covid-19 vaccine doses at a pace that's nearly five times faster than the global average, and has fully vaccinated a larger share of its population than most countries that have been vaccinating for a similar amount of time, a CNN analysis suggests.
Over the past week, the US administered an average of more than three million doses per day, according to data published by the US Centers for Disease Control and Prevention. That's more than 900 shots per 100,000 people each day.
Globally, an average of 16 million shots have been administered daily over the past week, according to data published by Our World in Data. That's about 200 shots per 100,000 people each day.
Outpacing other key countries:
Note: The UK has delayed second doses to get more people first doses. Find more specific country data at CNN's global vaccine tracker here.