The day after Thanksgiving is traditionally a quiet one on Wall Street. However, news doesn't stop just because it's a holiday, and new fears have futures contracts on U.S. stock market benchmarks down between 1% and 3% heading into Friday's holiday-shortened session. The Nasdaq Composite (^IXIC -0.25%) was holding up better than most of its peers, with futures falling 165 points to 16,201 as of 9 a.m. ET.

The threat of a new and potentially more infectious COVID-19 variant led to a rapid response from many governments around the world, prompting travel restrictions on those from South Africa, where the new variant first appeared. Yet even as many stocks fell sharply at the prospect of potentially seeing renewed economic and travel restrictions, Moderna (MRNA -9.07%) and Zoom Video Communications (ZM -2.04%) saw big gains in pre-market trading. Below, we'll take a closer look at the moves and how they might play out in the broader context of these businesses' long-term plans.

Will Moderna ride the wave?

Shares of Moderna were up more than 13% on Friday morning. That continued a bounce that had started shortly after the vaccine maker's nearly 40% plunge in early November.

Medical professional giving injection to patient.

Image source: Getty Images.

The reason for Moderna's rise on Friday is clearly connected to the new COVID-19 variant. Investors believe that there will be greater and longer-term demand for the vaccine that Moderna has developed, and they might also be looking for the company to come out with potential new versions that would fight this and future variants more effectively.

In many ways, though, the challenges that face Moderna remain unchanged. The stock's big drop earlier this month came as vaccine stock  rival Pfizer (PFE -2.03%) reported strong clinical results for its candidate antiviral treatment. Shareholders had worried that the availability of a pill to fight COVID-19 effectively after a patient contracts the disease might deter people from getting vaccines. Moreover, Pfizer's vaccine got approval from European regulators for administration for children five to 11 years old, while Canada gave Johnson & Johnson (JNJ -0.25%) the status of the first vaccine maker to get full regulatory approval.

Today's pop might well be warranted, but investors need to be prepared for continue volatility. Further developments will come at a rapid pace, and they could have dramatic impacts on Moderna's stock price.

Heading back to Zoom?

Meanwhile, Zoom Video Technologies posted a nearly 10% rise in pre-market trading Friday. The video collaboration platform provider had seen a big drop following its earnings report earlier this week, but some now believe that the need for remote communications will only increase in the face of the extended battle against the pandemic globally.

Zoom had performed poorly for most of 2021 as prospects for economic reopening around the world progressed. The loss of more than 60% in the stock price reached its nadir after its report of third-quarter financial results, which showed slowing revenue growth that threatened to stop entirely on a sequential basis. Earnings are also expected to remain flat in the fourth quarter compared to third-quarter levels, raising the question of what comes next for Zoom.

As with Moderna, though, the strategic challenges Zoom faces aren't going to get solved by prolonged concerns about new COVID-19 strains. Investments into areas like voice communication will have to pan out more favorably than they have in the past in order to justify Zoom's business decisions.

All in all, the big gains for both Zoom and Moderna shares appear to be kneejerk reactions from panicked traders on a day on which many professional investors are on vacation. Those who are working can expect a volatile Friday for these stocks and the market as a whole.