Coronavirus updates: Over 7,000 Americans died in past week

As he has repeatedly stressed throughout the pandemic, on Friday, the World Health Organization Director General Dr. Tedros Adhanom Ghebreyesus, once again urged countries to use all tools available to combat the virus, not just wait for a vaccine.

"There is no doubt that a vaccine will be a vital tool for controlling the pandemic, and we’re encouraged by the preliminary results of clinical trials released this week," Tedros said at the closing of the WHO's World Health Assembly.

"But we have a long way to go. The world cannot put all its eggs in one basket, and neglect the many other tools at our disposal that countries like Thailand have shown are effective for bringing this virus under control," he said. "The virus itself has not changed significantly, and nor have the measures needed to stop it. We know what works. First, know your epidemic and do the basics well. Find, isolate, test and care for cases. Trace and quarantine their contacts. And second, engage and empower communities to protect themselves and others with the full range of measures: physical distance, avoiding crowds, ventilation, hand hygiene, and masks," he said.

ABC News' Kirit M. Radia contributed to this report.

For the first time since the pandemic, official travel advisories have been issued for the West Coast.

As the leftover candy stash runs low in American households across the country, several state officials and school authorities have begun citing coronavirus outbreaks related to Halloween, less than two weeks after the fall holiday.

Throughout the pandemic, social gatherings and crowded venues, juxtaposed to the highly infectious virus, have resulted in a widespread escalation of COVID-19 cases across the country. Prior to Halloween, the CDC and other health experts had repeatedly warned Americans about the risk of contracting COVID-19 during the holiday, and in particular, at indoor costume gatherings.

Despite these warnings, some people still flouted recommendations.

Although several large events made headlines, such as a gathering in Utah, which reportedly attracted thousands of costumed attendees, other smaller events in private homes and dorm rooms seemingly slipped under the radar.

And now, officials say those events may be contributing to the surging COVID-19 case numbers seen in communities across the country.

As Oregon recorded its highest daily case figure on record on Thursday, health officials said that this week's rising case numbers could be traced to Halloween-related events; specifically, several small social gatherings, as well as a party with more than 100 people in attendance.

During a press conference earlier this week, California Gov. Gavin Newsom also said officials believe the state's recent increase in cases may be tied to Halloween celebrations. And as cases rise in Vermont, which has maintained relatively low COVID-19 case numbers throughout the pandemic, some COVID-19 clusters and outbreaks have been traced back to Halloween parties.

In Missouri's St. Louis County, a Halloween party has led to at least five positive COVID-19 cases, with possibly 200 high school students exposed to COVID-19, according to local officials, and following an increase in cases, the city of St. Louis Mayor Lyda Krewson announced new restrictions Thursday on private gatherings.

In New York, Suffolk County Executive Steve Bellone tied his community's "disturbing" rise in coronavirus cases to Halloween gatherings. Another county official in Onondaga County, New York called the recent COVID-19 uptick "the Halloween surge."

Colleges have also found themselves facing the consequences of students' desire to celebrate the holiday, as COVID-19 clusters pop up on campuses. In the last week, Tulane has reported over 300 new coronavirus cases, which the college president said were the result of "poor decisions" over the Halloween weekend.

The University of Tennessee-Knoxville has also identified a COVID-19 cluster connected to an off-campus gathering on Halloween.

Although it is ultimately difficult to measure how much these gatherings are actually contributing to the exponential surge the U.S. is currently experiencing, it is clear that when mitigation efforts are not followed at celebrations, COVID-19 cases may likely follow -- a worrisome trend heading into the winter holidays.

ABC News' Arielle Mitropolous and Ali Dukakis contributed to this report.

Dr. Vivek Murthy, the co-chair of President-elect Joe Biden's new coronavirus advisory board and former surgeon general, told "Good Morning America" Friday that targeted restrictions in specific areas, not a nationwide lockdown, would be the best path forward to combatting the virus.

"I think that's how we thought about it in the spring, but I think we've learned a lot since then about how this virus spreads and what we can do to reduce risk," he said. "And right now, the way we should be thinking about this is more like a series of restrictions that we dial up or down depending on how bad spread is taking place in a specific region."

He pointed to the success New York City has had in targeting areas down to the zip code. That approach, he said, also helps lessen the blow on the economy and COVID fatigue.

"We're not in a place where we're saying shut the whole country down. We got to be more targeted," Murthy said. "If we don't do that, what you're going to find is that people will become even more fatigued. Schools won't be open to children and the economy will be hit harder, so we've got to follow science, but we've also got to be more precise."

He said to combat the virus, the U.S. will focus on stopping the spread of COVID-19 by zeroing in on the hardest-hit communities and increasing testing.

"We still don't have adequate testing so anyone who wants a test can get one and get results quickly," Murthy told "GMA." "We still don't have enough testing to be able to do surveillance testing in universities and workplaces and in other places that are higher risk like prisons and nursing homes so that is an area where you'll see President-Elect Biden focusing expanding capacity."

States reported 151,000 cases in the U.S. on Thursday, with 67,000 people hospitalized with the virus, according to the COVID Tracking Project. Both figures are records.