Samantha Vinograd is a CNN national security analyst. She is a senior adviser at the University of Delaware's Biden Institute, which is not affiliated with the Biden campaign. Vinograd served on President Barack Obama's National Security Council from 2009 to 2013 and at the Treasury Department under President George W. Bush. Follow her @sam_vinograd . The views expressed in this commentary are her own. View more opinion articles on CNN.

(CNN) Donald Trump's coronavirus test came back negative after his exposure to an infected Brazilian official. But that doesn't guarantee a clean Covid-19 bill of health going forward. Because of the President's ongoing contact with countless numbers of people -- including White House staff -- he should be regularly screened and tested as appropriate.

Hopefully, he will now start following US Centers for Disease Control and Prevention guidelines to avoid turning the White House into a hot spot for infection.

The White House indeed showed some signs of added caution this weekend.

On Sunday, a doctor took the temperatures of the coronavirus task force members before they met and on Saturday journalists had to be checked for fever minutes before entering the briefing room for Trump's press conference. It's unclear if this new screening process will be applied consistently to White House staff, but in a time of crisis it is prudent to try to mitigate risk.

Overall, it's clear that Trump has taken unnecessary risks both with his own health and those around him by his refusal to get expeditiously tested after a confirmed exposure. Doctors have warned that people can be infected without running a fever.

A President's health is paramount -- it is critical to his ability to fully perform his responsibilities. Given the close quarters at the White House, it is imperative that the President protects himself and safeguards the health of those around him, whether it be staff, members of the American public or high-level foreign officials. POTUS as virus spreader is a situation everyone should want to avoid.

Even absent a pandemic, a president should be regularly monitored and screened for infection. I know from personal experience that the President is usually accompanied by a physician when he travels. During a health crisis like Covid-19, the President should be extra cautious about protecting himself from exposure and getting regularly screened and tested in line with existing guidelines.

Any president should lead by example -- especially during a crisis.

Instead, this time around, we have a President flouting the guidance the CDC is giving to millions of Americans. At 73, he's part of a high-risk group. Yet he resisted getting tested immediately despite being in close contact with people with the virus. His physician claimed he did not need to get checked (although the White House now says that he did ) or self-quarantine because he wasn't showing symptoms -- despite the CDC and other officials saying that some patients are asymptomatic.

And, with millions of people watching during a press conference on coronavirus, on Friday he personally engaged in the very behavior the CDC is warning against, like shaking hands and standing very close to people.

He may have tweeted on Saturday about " social distancing " but he's doing just the opposite. At all times, and especially during a complex crisis, presidential actions speak louder than words (or tweets).

It's fortunate for all who had contact with him that he reportedly tested negative, but trying to imagine what would happen if Americans followed the President's lead is terrifying.

If anyone wants misinformation during this national emergency, they need go no further than Twitter feed or the statements he makes at press conferences. Every day, he is sharing inaccurate information and lying about his own administration's strategy, as well as the actions of his perceived rivals, including his predecessor President Barack Obama

Whether it's talking about websites and tests that aren't widely available, or getting key details about a travel ban wrong, Trump poses health hazard to the American people. By failing to communicate clear and accurate information, he's confusing people about where and how to get potentially lifesaving testing.

A president should reassure the public during a crisis, not cause panic.

Nor is he showing any accountability. On Friday, he said he has no responsibility when it comes to our lack of preparedness -- even though this is happening on his watch. Plus, when pressed about why he closed the White House National Security Council directorate for global health and security -- charged with preventing and preparing for the next pandemic -- he threw his team under the bus, saying he personally didn't shut the office and pointing the finger at the people, rather than acknowledging any knowledge about why the office was shut down.

Back in February , he said the office was no longer needed. The office was shut down pursuant to guidance from then national security adviser John Bolton -- and typically presidents are briefed about NSC reorganizations.

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Trump broadcasting his lack of knowledge about key staff decisions isn't helpful and it doesn't address the fact that since the directorate was shut down in 2018 he hasn't pushed to increase personnel despite public warnings about pandemics -- including from the intelligence community -- over the last few years. Trump's scapegoating members of his own team just doesn't cut it -- he was grossly negligent when it came to getting ready for a new virus.

Presidents are entrusted to keep their citizens safe. When millions of Americans vote in November, they should consider whether they want to reelect a man who so willfully could put their health at risk.