A couple of years ago, who knew the names of companies such as Moderna and BioNTech would be so widely known? Thanks to their COVID-19 vaccines, they are now. But which other pharmaceutical companies are still likely to join these names, and those of Pfizer, AstraZeneca, and Johnson & Johnson, on the list of the world’s pandemic saviors?

There are still several firms that hope to introduce COVID-19 vaccines in the near future, and that have a good chance of doing so. Even if richer countries are getting significant supplies today, there’s a lot more of humanity to vaccinate—and possibly new mutations that will need addressing.

Here’s a rundown of four potentially serious players and what they have to offer.

CureVac

Who?

CureVac is the smallish, two-decade-old German biotech that President Donald Trump reportedly offered $1 billion to exclusively serve the U.S. The political fallout led the European Commission to loan the company €75 million ($90 million), while Germany invested €300 million for a 23% stake. The Bill & Melinda Gates Foundation has been an investor since 2015. CureVac had a successful Nasdaq IPO in August.

Vaccine name and type?

CVnCoV, a messenger RNA (mRNA) vaccine. This is a new kind of vaccine, in which synthesized ribonucleic acid is used to provoke the immune response. It is relatively easy to modify, but its freezing requirements have logistical implications.

When and where?

The vaccine could be one of the next to gain European Medicines Agency (EMA) approval, perhaps this or next month. However, CureVac hasn’t yet announced the efficacy of CVnCoV. The company already has a deal with the European Commission to provide up to 405 million doses to the EU’s 27 member states. It also has development agreements with Bayer and GlaxoSmithKline—and Bayer gets the option to market CVnCoV outside Europe.

Can it deliver?

CureVac says it can deliver up to 300 million doses this year, and much more in 2022. Partly using that EU loan, it’s building a factory in its hometown of Tübingen. However, its manufacturing muscle comes from partners. CureVac has agreements with contract manufacturers such as Rentschler Biopharma (for more than 100 million doses a year), Novartis (for up to 50 million doses this year and up to 200 million in 2022), Wacker Chemie (over 100 million doses a year), and Celonic (more than 100 million doses in total). Its GSK deal should also produce up to 100 million doses this year.

Novavax

Who?

Novavax is based in Gaithersburg, Md. It was founded in 1987, but is only now preparing to launch actual vaccines (also including a flu vaccine called NanoFlu). Before the pandemic, it appeared to be in a downward spiral owing to repeated failures of its vaccine candidates. The company received $1.6 billion from the Trump administration’s Operation Warp Speed and $388 million from the Coalition for Epidemic Preparedness Innovations (CEPI) to fund its COVID vaccine.

Vaccine name and type?

The Novavax COVID-19 vaccine, or NVX-CoV2373, or Covovax in its Indian trials. Novavax calls it a recombinant nanoparticle vaccine, and its production involves infecting moth cells with an insect virus that’s been modified to include the SARS-CoV-2 spike protein gene. The company says the vaccine has an efficacy rate of over 96%.

When and where?

Novavax is hoping for imminent approval in the U.S., the U.K., Canada, South Korea and the EU. Its Warp Speed deal should see it deliver 100 million doses in the U.S., while it has a 60 million dose contract in the U.K. and a Canadian deal for up to 76 million doses. Novavax was supposed to sign an EU deal for up to 200 million doses, but according to the European side it’s dragging its heels owing to problems sourcing raw materials. The company will however be supplying 1.45 billion doses to the Covax facility for low- and middle-income countries. It will also sell 40 million doses to South Korea.

Can it deliver?

Novavax’s Covax contribution includes 350 million doses that it will make itself, as well as 1.1 billion to be produced by the Serum Institute of India (SII), the world’s biggest vaccine manufacturer. At full capacity, the SII deal is supposed to pump out more than 2 billion doses a year. Novavax has said its own recently acquired facilities in the Czech Republic will have a capacity of over 1 billion doses annually. It also has manufacturing deals with Fujifilm Diosynth Biotechnologies (FDB) in the U.S. (100 million doses) and in the U.K. (180 million doses annually), Biofabri in Spain (over half a million doses), SK Bioscience in South Korea (40 million doses), and Takeda in Japan (over 250 million doses a year).

Sanofi and GlaxoSmithKline

Who?

Unlike CureVac and Novavax, these two are proper Big Pharma. Sanofi is a French multinational that’s been around since 1973, though its Sanofi Pasteur vaccine-making unit can trace its heritage back to the great microbiologist Louis Pasteur in the 19th century. GSK (which also has a hand in CureVac’s vaccine) is a British multinational that was born 21 years ago in the merger of Glaxo Wellcome and SmithKline Beecham. The pair got the biggest Operation Warp Speed award to fund their COVID-19 vaccine—$2.1 billion—and the U.S. Department of Health and Human Services is a codeveloper.

Vaccine name and type?

Sanofi-GSK COVID-19 vaccine, or VAT00002. It’s an adjuvanted recombinant protein-based vaccine, essentially a tweaked version of an existing Sanofi flu vaccine that uses a SARS-CoV-2 spike protein rather than an influenza protein, with GSK providing the adjuvant (a component that aims to boost immune response). Sanofi is also working separately with Translate Bio on an mRNA vaccine candidate.

When and where?

The Sanofi-GSK vaccine has suffered significant setbacks. Thanks to a dosing miscalculation, clinical trials last year showed insufficient immune responses in older people, leading the companies to begin fresh trials in February. They are now targeting approval in Q4, meaning their vaccine is (if successful by that point) most likely to be used to address emerging COVID variants. Deals already signed include those with the European Commission (up to 300 million doses), the U.S. (an initial 100 million doses with the option for 500 million more), Canada (up to 72 million doses), the U.K. (up to 60 million doses), and the Covax facility (20 million doses).

Can they deliver?

Again, these are established Big Pharma firms so, if the vaccine proves effective, sure.

Valneva

Who?

Valneva is a French vaccine specialist that’s all of eight years old. It already sells vaccines against cholera and Japanese encephalitis. This week it announced a share flotation to raise more than $100 million for the development of its COVID vaccine.

Vaccine name and type?

Valneva COVID-19 vaccine, or VLA2001. This one’s a traditional inactivated whole virus vaccine, meaning it delivers a killed-off version of the SARS-CoV-2 virus itself into the body in order to stimulate the immune response. The approach could be useful in targeting COVID variants because it doesn’t focus so exclusively on the spike protein where some of the most dangerous mutations occur. Phase I/II trials have shown Valneva’s vaccine to be “generally safe and well tolerated.”

When and where?

Valneva is hoping to apply for regulatory approval in the fall, pending successful Phase III trial data. Valneva’s big contract—for up to 190 million doses by 2025—is with the U.K., where its manufacturing is based. Talks with the EU collapsed last month, with the European Commission claiming Valneva didn’t meet “a certain set of conditions.” However, France and some other EU countries are reportedly still keen to buy the firm’s vaccine on a bilateral basis, if it pans out.

Can it deliver?

So far, Valneva only has one plant, in Scotland; it’s supposed to pump out 200 million doses a year. The company said in February that it was open to other production partnerships if enough customers materialize.