A strong showing by Democratic presidential candidate Joe Biden on Super Tuesday sparked a broad-based rally in health-care stocks Wednesday, sending United Health Group Inc. up more than 12% for its biggest one-day gain since October of 2008.

Health-care stocks have been rocked each time rival Bernie Sanders has gained ground over rivals for the Democratic nomination on fears his “Medicare for All” plan would crush private insurers and drugmakers.

Sanders’ proposal is for a national health insurance program that would cover many services without premiums, deductibles, copays or unexpected pharmaceutical bills, “leading to the termination of existing health insurance plans,” according to CFRA analyst Sel Hardy.

Biden is viewed as a safer pair of hands, who has said he would fight to preserve the Affordable Care Act that he helped shepherd through in his role as vice president to former President Barack Obama.

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“In terms of our overall outlook for our stocks, unless there is a major shift in market conditions, Centene Corp. US:CNC, UnitedHealth US:UNH, Humana Inc. US:HUM, and Cigna Corp. US:CI are set for double-digit top-line growth in the next three years, in our view, as they continue to have strong fundamentals,” Hardy wrote in a note to clients.

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Centene was last up 8%, Cigna was up 11%, Humana gained 12%5, Molina Healthcare US:MOH rose 13% and Anthem Inc. US:ANTM was up 14%.

Among hospital operators, shares of Community Health Systems Inc. US:CYH jumped 6%, HCA Healthcare Inc. US:HCA rose 7% and Tenet Healthcare Corp. US:THC, was up 8%.

Elsewhere in the sector, stocks of companies that are working to develop vaccines, tests or other treatments for the coronavirus that has sickened more than 93,000 people around the world and caused more than 3,100 deaths, were also mostly higher.

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Shares of Inovio Pharmaceuticals Inc. US:INO rallied another 20%, a day after the company said it’s accelerating the timeline for development of a vaccine to treat the coronavirus and expects to start human trials in the U.S. next month. The stock has now gained 261% in three months.

Plymouth Meeting, Pennsylvania-based Inovio specializes in developing DNA vaccines and has created products to treat 15 indications. It is the only company to have a phase 2 vaccine for the coronavirus that caused Middle East respiratory syndrome, or MERS. The company was called on to help during the 2016 Zika outbreak and the Ebola outbreak in 2014.

Inovio Chief Executive Dr. J. Joseph Kim told the U.S. Coronavirus Task Force meeting at the White House on Monday that the company designed INO-4800 on Jan. 10 in three hours after the publication of the genetic sequence of the virus. The company quickly moved to preclinical testing and expects to be able to deliver 1 million doses of vaccine by year-end.

Stifel analysts said they caught up with Inovio management late Tuesday and are confident the company is in a good position to work on the virus.

“We believe Inovio’s ongoing clinical development of a MERS-targeting vaccine (a related coronavirus) provides leverageable experience and believe the company’s nucleic acid based vaccine technology – while still unproven in larger outcomes studies (only P1 safety/immunogenicity data has been generated for any infectious disease vaccine candidate) – provides meaningful advantages on the manufacturing/production fronts (the timing of which likely represents a rate-limiting step for traditional vaccine technologies),” analysts led by Stephen Willey wrote in a note Wednesday. Stifel rates the stock a buy.

Vir Biotechnology Inc. US:VIR shares rose 12% and Alnylam Pharmaceuticals Inc. US:ALNY rose 2.4%, after the companies said they would expand their cooperation agreement to advance RNAi Therapeutics for the treatment of the coronavirus.

“Recent Alnylam advances in lung delivery technology suggest possible utility of siRNAs in targeting SARS-CoV-2 and other coronaviruses,” the companies said in a joint statement.

Takeda Pharmaceutical Company Ltd. US:TAK rose 5.4% after the Japanese company unveiled plans to test a hyperimmune globulin treatment for people at high risk for the coronavirus and will share those development plans with members of Congress. Like several other drugmakers, it also said it is examining its current portfolio of therapies and treatment candidates for other diseases to see if there is an application for the virus.

Pfizer Inc. US:PFE shares were up 3.7%, after the company said it too is screening antiviral drugs in its development pipeline to determine whether they could be effective in treating the illness. Shares of AbbVie Inc. US:ABBV, which has donated doses of an HIV treatment to China as a potential treatment option, were up 3.2%

AIM ImmunoTech Inc. US:AIM, which is working with ChinaGoAbroad to bring its experimental drug Ampligen into China as a treatment for the virus, was up 25%. But Moderna Inc. US:MRNA, which said last week it had shipped the first COVID-19 vaccine candidate to the National Institutes of Health for clinical trials, was down 1.6%. Gilead Inc. US:GILD, which is also developing a vaccine, was up 1.1%.

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The SPDR Health Care Select Sector exchange-traded fund US:XLV was up 3.5%, while the S&P 500 index US:SPX was up 1.9% and the Dow Jones Industrial Average US:DJIA was up 2.1%.