- The FDA and CDC recently authorized the distribution of Johnson & Johnson's COVID-19 vaccine.
- It will soon be the third vaccine available in the U.S., the other two being vaccines produced by Pfizer-BioNTech and Moderna.
- The new vaccine has a lower efficacy rate, but clinical data suggest its highly effective at preventing hospitalization and death.
A Food and Drug Administration committee is set to vote Friday (February 26) on recommending the approval of Johnson & Johnson's COVID-19 vaccine for emergency use. If the FDA's Vaccines and Related Biological Products Advisory Committee recommends approval, the next step would be getting a green light from the Centers for Disease Control and Prevention, which could authorize the distribution of up to 4 million doses of the vaccine as early as next week.
Approval from the CDC would make Johnson & Johnson's vaccine the third available vaccine in the U.S., joining those currently being distributed by Pfizer-BioNTech and Moderna. The U.S. government has already purchased 100 million doses of the Johnson & Johnson vaccine.
On Wednesday, the FDA released an analysis of clinical trial data on Johnson & Johnson's vaccine saying "there were no specific safety concerns identified in subgroup analyses by age, race, ethnicity, medical comorbidities, or prior SARS-CoV-2 infection," and that the vaccine was "consistent with the recommendations set forth in FDA's guidance Emergency Use Authorization for Vaccines to Prevent COVID-19."
So, what are the key differences between the three vaccines?
Credit: Mediteraneo via Adobe Stock
What makes Johnson & Johnson's vaccine unique is that it's effective after just one dose, while the vaccines produced by Pfizer-BioNTech and Moderna require two doses administered over several weeks.
And unlike the other two vaccines, Johnson & Johnson's vaccine doesn't need to be frozen during shipping and storage, it just needs to be refrigerated. That's because the vaccine protects against COVID-19 by delivering coronavirus proteins to the body through a common cold virus known as adenovirus type 26. In contrast, the other two vaccines perform a similar function, but they do it through mRNA, which is more delicate and requires freezing.
Not having to freeze the single-shot vaccine will make it cheaper and easier to distribute across the country, and it could result in many more people getting vaccinated.
But it's worth noting that Johnson & Johnson's vaccine doesn't seem to be as effective as the other two vaccines. According to the FDA analysis, the vaccine is about 66 percent effective at preventing moderate to severe cases of COVID-19, "when considering cases occurring at least 28 days after vaccination." Meanwhile, clinical data show that the Pfizer-BioNTech and Moderna vaccines are about 95 percent effective at preventing severe cases of the disease.
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Still, that doesn't necessarily mean Johnson & Johnson's vaccine is inferior. The FDA analysis found that nobody who received the Johnson & Johnson vaccine was hospitalized or died due to COVID-19 (at least among cases that occurred 28 days after getting the shot).
So, while some people who receive the Johnson & Johnson vaccine may still contract coronavirus, the vaccine does seem to significantly reduce the severity of COVID-19. The same holds true for the other two vaccines: Getting the shot (or shots) won't completely protect you from the virus, but it does protect you from the disease, reducing the chances of becoming hospitalized or dying to almost zero.
COVID-19 vaccines and transmission
But what's less clear is the extent to which the vaccines prevent the spread of the novel coronavirus. Because the vaccines don't completely protect against infection, it might be possible for a vaccinated person to spread the virus. But COVID-19 vaccines might make transmission less likely.
After all, even if a person who gets vaccinated contracts the coronavirus, the virus would have a harder time replicating in their body, because the vaccine bolsters the immune response. So, one would expect that person to "shed" less of the virus out of their mouth and nose. In short: fewer infections means less replication, less shedding, and less transmission.
That's the theory, anyway.
Scientists are still working to understand how exactly these vaccines affect transmission. But early data is promising. In a preprint paper published on medRxiv, Israeli researchers measured the amount of coronavirus within about 2,900 people who had received the Pfizer-BioNTech vaccine.
"Analyzing positive SARS-CoV-2 test results following inoculation with the BNT162b2 mRNA vaccine [the Pfizer vaccine], we find that the viral load is reduced four-fold for infections occurring 12-28 days after the first dose of vaccine," the paper said. "These reduced viral loads hint to lower infectiousness, further contributing to vaccine impact on virus spread."
But until the data on vaccines and transmission become clear, the CDC recommends that vaccinated people still wear masks and practice social distancing.
UPDATE: The CDC voted on Sunday to recommend the vaccine for the United States. CDC Director Dr. Rochelle Walensky signed off on the recommendation.
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Our hearts beat at a resting rate of 60 to 100 beats per minute. Lots of other things pulse, too. The colors we see and the pitches we hear, for example, are due to the different wave frequencies ("pulses") of light and sound waves.
Now, a study in the journal Geoscience Frontiers finds that Earth itself has a pulse, with one "beat" every 27.5 million years. That's the rate at which major geological events have been occurring as far back as geologists can tell.
A planetary calendar has 10 dates in red
Credit: Jagoush / Adobe Stock
According to lead author and geologist Michael Rampino of New York University's Department of Biology, "Many geologists believe that geological events are random over time. But our study provides statistical evidence for a common cycle, suggesting that these geologic events are correlated and not random."
The new study is not the first time that there's been a suggestion of a planetary geologic cycle, but it's only with recent refinements in radioisotopic dating techniques that there's evidence supporting the theory. The authors of the study collected the latest, best dating for 89 known geologic events over the last 260 million years:
- 29 sea level fluctuations
- 12 marine extinctions
- 9 land-based extinctions
- 10 periods of low ocean oxygenation
- 13 gigantic flood basalt volcanic eruptions
- 8 changes in the rate of seafloor spread
- 8 times there were global pulsations in interplate magmatism
The dates provided the scientists a new timetable of Earth's geologic history.
Tick, tick, boom
Credit: New York University
Putting all the events together, the scientists performed a series of statistical analyses that revealed that events tend to cluster around 10 different dates, with peak activity occurring every 27.5 million years. Between the ten busy periods, the number of events dropped sharply, approaching zero.
Perhaps the most fascinating question that remains unanswered for now is exactly why this is happening. The authors of the study suggest two possibilities:
"The correlations and cyclicity seen in the geologic episodes may be entirely a function of global internal Earth dynamics affecting global tectonics and climate, but similar cycles in the Earth's orbit in the Solar System and in the Galaxy might be pacing these events. Whatever the origins of these cyclical episodes, their occurrences support the case for a largely periodic, coordinated, and intermittently catastrophic geologic record, which is quite different from the views held by most geologists."
Assuming the researchers' calculations are at least roughly correct — the authors note that different statistical formulas may result in further refinement of their conclusions — there's no need to worry that we're about to be thumped by another planetary heartbeat. The last occurred some seven million years ago, meaning the next won't happen for about another 20 million years.
When I was a junior in college, my electromagnetism professor had an awesome idea. Apart from the usual homework and exams, we were to give a seminar to the class on a topic of our choosing. The idea was to gauge which area of physics we would be interested in following professionally.
Professor Gilson Carneiro knew I was interested in cosmology and suggested a book by Nobel Prize Laureate Steven Weinberg: The First Three Minutes: A Modern View of the Origin of the Universe. I still have my original copy in Portuguese, from 1979, that emanates a musty tropical smell, sitting on my bookshelf side-by-side with the American version, a Bantam edition from 1979.
Inspired by Steven Weinberg
Books can change lives. They can illuminate the path ahead. In my case, there is no question that Weinberg's book blew my teenage mind. I decided, then and there, that I would become a cosmologist working on the physics of the early universe. The first three minutes of cosmic existence — what could be more exciting for a young physicist than trying to uncover the mystery of creation itself and the origin of the universe, matter, and stars? Weinberg quickly became my modern physics hero, the one I wanted to emulate professionally. Sadly, he passed away July 23rd, leaving a huge void for a generation of physicists.
What excited my young imagination was that science could actually make sense of the very early universe, meaning that theories could be validated and ideas could be tested against real data. Cosmology, as a science, only really took off after Einstein published his paper on the shape of the universe in 1917, two years after his groundbreaking paper on the theory of general relativity, the one explaining how we can interpret gravity as the curvature of spacetime. Matter doesn't "bend" time, but it affects how quickly it flows. (See last week's essay on what happens when you fall into a black hole).
The Big Bang Theory
For most of the 20th century, cosmology lived in the realm of theoretical speculation. One model proposed that the universe started from a small, hot, dense plasma billions of years ago and has been expanding ever since — the Big Bang model; another suggested that the cosmos stands still and that the changes astronomers see are mostly local — the steady state model.
Competing models are essential to science but so is data to help us discriminate among them. In the mid 1960s, a decisive discovery changed the game forever. Arno Penzias and Robert Wilson accidentally discovered the cosmic microwave background radiation (CMB), a fossil from the early universe predicted to exist by George Gamow, Ralph Alpher, and Robert Herman in their Big Bang model. (Alpher and Herman published a lovely account of the history here.) The CMB is a bath of microwave photons that permeates the whole of space, a remnant from the epoch when the first hydrogen atoms were forged, some 400,000 years after the bang.
The existence of the CMB was the smoking gun confirming the Big Bang model. From that moment on, a series of spectacular observatories and detectors, both on land and in space, have extracted huge amounts of information from the properties of the CMB, a bit like paleontologists that excavate the remains of dinosaurs and dig for more bones to get details of a past long gone.
How far back can we go?
Confirming the general outline of the Big Bang model changed our cosmic view. The universe, like you and me, has a history, a past waiting to be explored. How far back in time could we dig? Was there some ultimate wall we cannot pass?
Because matter gets hot as it gets squeezed, going back in time meant looking at matter and radiation at higher and higher temperatures. There is a simple relation that connects the age of the universe and its temperature, measured in terms of the temperature of photons (the particles of visible light and other forms of invisible radiation). The fun thing is that matter breaks down as the temperature increases. So, going back in time means looking at matter at more and more primitive states of organization. After the CMB formed 400,000 years after the bang, there were hydrogen atoms. Before, there weren't. The universe was filled with a primordial soup of particles: protons, neutrons, electrons, photons, and neutrinos, the ghostly particles that cross planets and people unscathed. Also, there were very light atomic nuclei, such as deuterium and tritium (both heavier cousins of hydrogen), helium, and lithium.
Cosmic alchemy
So, to study the universe after 400,000 years, we need to use atomic physics, at least until large clumps of matter aggregate due to gravity and start to collapse to form the first stars, a few millions of years after. What about earlier on? The cosmic history is broken down into chunks of time, each the realm of different kinds of physics. Before atoms form, all the way to about a second after the Big Bang, it's nuclear physics time. That's why Weinberg brilliantly titled his book The First Three Minutes. It is during the interval between one-hundredth of a second and three minutes that the light atomic nuclei (made of protons and neutrons) formed, a process called, with poetic flair, primordial nucleosynthesis. Protons collided with neutrons and, sometimes, stuck together due to the attractive strong nuclear force. Why did only a few light nuclei form then? Because the expansion of the universe made it hard for the particles to find each other.
What about the nuclei of heavier elements, like carbon, oxygen, calcium, gold? The answer is beautiful: all the elements of the periodic table after lithium were made and continue to be made in stars, the true cosmic alchemists. Hydrogen eventually becomes people if you wait long enough. At least in this universe.
In this article, we got all the way up to nucleosynthesis, the forging of the first atomic nuclei when the universe was a minute old. What about earlier on? How close to the beginning, to t = 0, can science get? Stay tuned, and we will continue next week.
To Steven Weinberg, with gratitude, for all that you taught us about the universe.
