Here’s how the top 3 coronavirus vaccine candidates stack up

AstraZeneca (NASDAQ: AZN) recently became the third company in as many weeks to report positive interim results from a large randomized study with an investigational coronavirus vaccine.

How does AstraZeneca’s candidate compare to investigational Pfizer (NYSE: PFE) and Modern (NASDAQ: ARNM) who are only a few steps ahead? As you might expect, different candidates have their own strengths and weaknesses. Here’s how they stack up against based on what we’ve learned so far.

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Current candidate vaccines have similar levels of safety.

AstraZeneca’s candidate AZD1222 uses a weakened virus derived from a common cold known to infect only chimpanzees. The non-replicating viral vector provides genetic instructions for advanced proteins found on the surface of SARS-CoV-2, the virus responsible for COVID-19. Moderna and Pfizer mRNA-1273 and its collaborative partner BioNTechof (NASDAQ: BNTX) Both BNT162b2 deliver strands of messenger RNA (mRNA) that instruct human cells to make copies of the same spike protein.

These candidate vaccines gave us no reason to be concerned about potential side effects, but only a few treatments using viral vectors have been approved by the Food and Drug Administration, and none of them were vaccines. Drugs that use mRNA stands are even less well understood because BNT162b2 and mRNA-1273 were the first to show clear signs of efficacy in a phase 3 study.

Efficiency

AstraZeneca performed its interim analysis after 131 positive cases of COVID-19 emerged among the first volunteers to join ongoing Phase 3 studies in the UK and Brazil. Only 30 positive COVID-19 readings occurred among patients randomized to receive the vaccine, none severe enough to require hospitalization.

A group of about 2,700 volunteers who initially received a half-dose of AZD1222 followed by a full-size booster shot were 90% less likely to test positive than patients given a placebo. Unfortunately, the interim analysis included around 8,900 volunteers in the UK and Brazil who received two full doses.

For mysterious reasons, the vaccine was only shown to be 62% effective in patients who received two full doses of AZD1222. The complete absence of COVID-19 hospitalizations among volunteers randomized to receive AZD1222 is a significant achievement, but AstraZeneca has still not told us how many cases of COVID-19 in the placebo group became serious.

MRNA-based candidates so far lead AstraZeneca’s candidate in the efficiency department. Of the first 170 volunteers in Pfizer’s Phase 3 trial to test positive, only eight were randomized to receive BNT162b2. Nine cases in the placebo group became serious, compared with a single person who received the actual vaccine candidate.

Of the first 95 volunteers to test positive in the pivotal Moderna coronavirus vaccine trial, only five were in the placebo group. This suggests that mRNA-1273 is 94.5% effective in preventing people from testing positive for COVID-19, which is slightly lower than the 95% effectiveness score presented by Pfizer and BioNTech.

Before calling the most effective Pfizer candidate, it’s important to remember that a volunteer randomized to receive BNT162b2 has developed a severe case of COVID-19. This did not happen to any volunteers who received mRNA-1273 or AZD1222.

Logistics

There are clear logistical distinctions between the three most advanced coronavirus vaccine candidates. With genetic information wrapped in a viral vector, the AstraZeneca candidate is much easier to store and transport than the vaccine candidates from Pfizer and Moderna. AZD1222 can be stored, transported, and handled for at least six months at normal refrigerator temperatures between 36 degrees and 46 degrees Fahrenheit.

Since BNT162b2 and mRNA-1273 are encapsulated in relatively unstable layers of lipid nanoparticles, they must be kept much cooler than AZD1222. Pfizer’s mRNA vaccine candidate should be stored at an ultra-cold temperature minus 94 degrees Fahrenheit. Once taken out of the freezer, BNT162b2 should be discarded if it remains at normal refrigerator temperature for more than 24 hours.

In the logistics department, Moderna’s vaccine candidate falls between AZD1222 and BNT162b2 with a required six-month storage temperature of minus 4 degrees Fahrenheit or less. Lipids encapsulating mRNA-1273 will remain stable at standard refrigerator temperatures for up to 30 days after removal from the freezer.

Another tight race

Whenever you compare the results of clinical trials from different populations, you are also comparing the results of different populations. Without head-to-head studies between the best vaccine candidates, differences in efficacy should be taken with a grain of salt.

We can’t be sure which vaccine candidate will become the most popular, but we know there will be a lot of competition. Keep this in mind if you plan to buy biotech stocks driven by their coronavirus vaccination programs.