Australia Why vaccine efficacy and effectiveness are not the same thing

03:15  09 april  2021
03:15  09 april  2021 Source:   abc.net.au

A Terrible Conundrum for the AstraZeneca Vaccine

  A Terrible Conundrum for the AstraZeneca Vaccine For the moment, reports of a very rare, dangerous blood disorder among recipients cannot be ignored.That’s why the past few weeks have felt so catastrophic.

The two terms used to describe how well a drug or vaccine works are often used interchangeably, but they are not actually the same thing – here’s why . 18 November 2020. A vaccine with an efficacy of 90% in a trial, for instance, means there was a 90% reduction in cases of disease in the vaccinated group compared to the unvaccinated (or placebo) group. But efficacy in laboratory conditions does not always translate to effectiveness , and so an efficacy trial can overestimate a vaccine ’s impact in practice.

No, vaccines are never 100% effective . Some vaccine approach that -- smallpox vaccine was about 95% effective , measles vaccine is about 98% , yellow fever vaccine may be 99% -- but this is biology; almost nothing is 100%. Why not? It could be Really dumb ideas are like starlings. They tend to flock together. Now it’s interesting to ask why this might be the case (the flocks of daft questions, not the flocks of starlings, although that too is interesting [1] ). I suspect it’s something to do with failing to learn how (a) logic and maths works—especially statistics (b) good science works—and why it’s not

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CoronaCheck #60

In this week's CoronaCheck, we explain what, exactly, vaccine efficacy figures mean and take a look at the evidence for and against ivermectin as a COVID-19 treatment.

We also gather up fact checking from the US about proposed changes to the nation's voting laws, and outline some tips and tricks from Google on spotting online misinformation.

Doctor reveals 'worrying' symptoms to look for after AstraZeneca jab

  Doctor reveals 'worrying' symptoms to look for after AstraZeneca jab One of Australia's leading doctors has revealed the warning signs people need to look out for after a man was hospitalised with a rare blood clotting condition after he received the AstraZeneca jab.Acting Chief Medical Officer Michael Kidd addressed concerns surrounding the vaccine on Friday.

Overview of Vaccine Efficacy and Vaccine Effectiveness . Shelly McNeil, MD. Canadian Center for Vaccinology Dalhousie University Halifax, Nova Scotia Canada. n Vaccine efficacy - % reduction in disease incidence in a vaccinated group compared to an unvaccinated group under optimal conditions (eg RCT) n Typically use objective outcomes- eg lab-confirmed influenza n designed to maximize internal validity (by randomization and allocation concealment) n often at the expense of generalizability.

Vaccine efficacy and effectiveness are measures that compare the rates of disease between vaccinated and unvaccinated people. Efficacy is measured in controlled clinical trials, whereas effectiveness is measured once the vaccine is approved for use in the general population. From these we can identify the proportion of vaccinated people we would expect to be protected by the vaccine . Herd immunity (also called community immunity) is an important mechanism by which the larger community is protected. For some diseases, if enough people are immune then transmission of the

Vaccine efficacy versus effectiveness

For months, we've been hearing that COVID-19 vaccines are up to 95 per cent effective, but what does that figure actually represent?

First, it's important to understand the difference between vaccine efficacy and vaccine effectiveness, even though the terms are sometimes used interchangeably.

According to , a partnership between the World Health Organisation, UNICEF, the World Bank and the Bill and Melinda Gates Foundation which is co-leading the COVAX program to distribute COVID-19 vaccines in developing nations, "efficacy" refers to the degree to which a vaccine prevents disease in controlled circumstances such as a clinical trial, while effectiveness measures real-world results.

Australia's rollout of AstraZeneca Covid vaccine will NOT be paused

  Australia's rollout of AstraZeneca Covid vaccine will NOT be paused Australia's rollout of the AstraZeneca vaccine will continue despite growing fears the jab could be related to a blood clotting condition reported in some patients. Acting Chief Medical Officer Michael Kidd has dismissed suggestions the vaccine poses any serious threat and the government's medical advice remains unchanged despite a man being hospitalised with a rare blood clotting condition after receiving it.

ing Influenza Vaccine Efficacy and Effectiveness Studies. Published for the 2010-11 Influenza Season; Adapted for. the 2012-13 Inuenza Season. Gastroenterologist knowledge of the appropriate immunizations to recommend to the IBD patient is poor and may be the primary reason why the majority of gastroenterologists believe that the PCP should be responsible for vaccinations . Educational programs on vaccinations directed to gastroenterologists who prescribe immunosuppressive agents are needed.

The first thing I want to say here is that the type of vaccine being developed against Covid-19 has never been used before, outside of Ebola. Some people feel that they should not really be called vaccines , because they are completely different from anything that has gone before. The first ever ‘ vaccine ’ worked by using the cowpox virus to immunise against smallpox. It had been noticed that milkmaids who caught cowpox, a relatively mild disease in humans, did not then get smallpox. It was Edward Jenner who wondered how, or why , this happened.

"Although a vaccine that has high efficacy — such as Moderna's COVID-19 vaccine with 94.5 per cent efficacy and Pfizer's with 90 per cent efficacy — would be expected to be highly effective in the real world, it is unlikely to translate into the same effectiveness in practice," a Gavi  reads.

Recent updates from  and  — the drug manufacturers responsible for the COVID-19 jabs available in Australia — suggest that the two vaccines have efficacy rates of 91.3 per cent and 76 per cent respectively, with  compiled by Israel's Ministry of Health showing the Pfizer vaccine to be 97 per cent effective.

But what, exactly, are the vaccines effective at doing?

Pfizer itself  vaccine efficacy in terms of how well the jab works to prevent "symptomatic disease, severe/critical disease and death".

As David Spiegelhalter, the chair of the Winton Centre for Risk and Evidence Communication at Cambridge University, and Anthony Masters, a statistical ambassador for the Royal Statistical Society, , a 90 per cent efficacy rate does not mean an individual has a 10 per cent chance of contracting COVID-19.

Decision about AstraZeneca's use in Australia to be make this week

  Decision about AstraZeneca's use in Australia to be make this week An urgent investigation was launched into the potential side effects of the Covid-19 vaccine after a Melbourne man who received the jab was hospitalised with a rare blood clotting condition. Experts have been holding talks with European regulators to determine whether the 44-year-old's low blood platelets and 22 other similar cases in the UK are linked to the vaccine. The Australian Technical Advisory Group on Immunisation (ATAGI) will convene on Wednesday to weigh up the risks and benefits of AstraZeneca jabs once further information is provided from international discussions.

THE MODERNA vaccine is being rolled out in the UK, the third coronavirus vaccine in the UK programme. While reports show the efficacy against variants could be higher, some have reported worse side effects. Comparatively, 68.6 percent of those given the second Pfizer jab reported injections site reactions and 64.2 percent had other symptoms. Why more people report side effects from the Moderna jab is as yet unclear, but authorities are assuring the public they are usually mild and manageable, and should not be a deterrent to getting vaccinated .

A dip in the vaccines ' effectiveness would be "all the more reason why we should be vaccinating as many people as you possibly can," Fauci added. Some early findings that were published in the preprint server bioRxiv, which have yet to be peer reviewed, indicate that the variant identified in South Africa, known as 501Y.V2, can evade the antibodies provided by some coronavirus treatments and may reduce the efficacy of the current line of available vaccines .

"Imagine 100 people are ill with COVID-19," the experts explained. "‘Ninety per cent efficacy' means if only they'd had the vaccine, on average only 10 would have got ill.

"Vaccine efficacy is the relative reduction in the risk: whatever your risk was before, it is reduced by 90 per cent if you get vaccinated. There is a lot of confusion about this number: it does not mean there is a 10 per cent chance of getting COVID-19 if vaccinated — that chance will be massively lower than 10 per cent."

While that is likely to placate concerns around the toll of COVID-19 on health at an individual level, it doesn't mean that a healthy vaccinated person cannot spread the disease.

Experts  explained that efficacy figures refer to how good the vaccines are at preventing illness, rather than how good they are at stopping you from being infected with COVID-19 altogether.

"In clinical trials, the Pfizer vaccine was found to be 95 per cent effective at reducing disease," the ABC reported. "But whether it stopped people from getting infected in the first place isn't yet known — because it wasn't measured."

Young Australians' hopes for an overseas holiday could be dashed

  Young Australians' hopes for an overseas holiday could be dashed Australia had been aiming to open its international borders beyond New Zealand from the end of October when every citizen was expected to receive at least their first vaccine dose. But that timeline is now almost impossible to meet following Thursday's announcement the AstraZeneca Covid-19 vaccine - which Australia had purchased the most doses of - was no longer recommended for under 50s, only the Pfizer jab.

As Larisa Labzin, an immunologist at the University of Queensland, told the ABC, it is possible that people in Pfizer's clinical trials were infected with COVID-19 but did not develop symptoms.

These people would not have been identified or included in Pfizer's analysis, as the researchers only looked at whether the vaccine prevented or reduced the severity of COVID-19 symptoms.

AstraZeneca researchers, on the other hand, tested participants for COVID-19 regardless of whether they showed any symptoms, and found a 67 per cent reduction in infections after a single vaccine dose, according to  in The Conversation written by experts from RMIT University.

There was also evidence that trial participants who tested positive despite receiving the AstraZeneca vaccine shed the virus over shorter periods of time.

"This data suggests the AstraZeneca vaccine also has potential to substantially affect virus transmission, by reducing the number of highly infectious people in a population," the RMIT researchers concluded.

The facts about ivermectin

Promoted ad nauseum as a potential COVID-19 cure by now-independent federal MP Craig Kelly, ivermectin, the active ingredient in medicines used to treat various parasitic infections, has  for use in treating COVID-19 outside of clinical trials in Australia.

It’s Not Over for the J&J Vaccine

  It’s Not Over for the J&J Vaccine A pause is just that—a pause—in which health officials can reevaluate the data at hand.Experts haven’t yet conclusively determined whether J&J’s vaccine is directly causing these strange clots, or how frequently the condition might be occurring, because they’re relying largely on people reporting their health conditions to federal agencies. Roughly 7 million doses of the vaccine have been administered so far in the United States; among them were about 1 million women under the age of 50. “I think it’s reasonable to say it is a rare event, but I don’t think we should go into false precision in this kind of situation,” Saad Omer, a vaccine expert at Yale, told me.

Australia's medicines regulator, the Therapeutic Goods Administration, there is currently "insufficient evidence to support the safe and effective use of ivermectin… for the prevention or treatment of COVID-19".

US drug manufacturer Merck, which produces and distributes ivermectin, agrees, stating in  that there was "no scientific basis for a potential therapeutic effect against COVID-19 from pre-clinical studies".

Regardless, Mr Kelly's social media posts, including a post , suggest that a slew of scientific studies have found the drug to be an effective COVID-19 treatment.

So, what are the facts?

Back in December, fact checkers at the Associated Press  there was no evidence ivermectin was a safe or effective treatment against COVID-19.

"Dr Amesh Adalja, an infectious disease expert at Johns Hopkins University, said most of the research around ivermectin at the moment is made up of anecdotes and studies that are not the gold standard in terms of how to use ivermectin," AP reported.

More recently, experts interviewed by  agreed that more research was needed to determine the drug's efficacy.

"To be sure about the effectiveness of ivermectin, we need to conduct larger clinical trials, which we don't have at the moment," Nairobi-based epidemiologist Emanuel Okunga told AFP Fact Check.

Australia's COVID-19 Clinical Evidence Taskforce concurs, telling Fact Check in an email that current research "does not demonstrate the effectiveness of ivermectin in the treatment of COVID-19".

"Our assessment is that the certainty of the current evidence is low for mortality, invasive mechanical ventilation, adverse or serious events, discharge from hospital, admission to ICU and clinical improvement," a statement from the taskforce said.

Got a COVID vaccine question? Ask our medical experts in the ABC coronavirus blog

  Got a COVID vaccine question? Ask our medical experts in the ABC coronavirus blog To bring you up to speed, here's a rundown of common COVID vaccines and where they fit into Australia's vaccination rollout.Associate professor Hassan Vally from La Trobe University and the ABC's national medical reporter Sophie Scott will be answering questions in the COVID blog from 11:00am AEST.

"Certainty is very low for viral clearance, time to clinical recovery and duration of hospital stay."

This, the taskforce added, was due to "very serious imprecision" in the evidence available, including "reliance on a single study, limited number of patients, and/or wide confidence intervals".

"Given this uncertainty of benefit, and concerns of harms; we recommend that ivermectin only be provided in research trials, where there is the potential to generate further evidence on the effectiveness, or otherwise, of ivermectin."

One oft-cited  supposedly showing promising signs that ivermectin could be used to treat COVID-19 was published by Australian researchers in June 2020.

fact checkers at AP, the study showed that "ivermectin inhibited the replication of SARS-CoV-2 in a laboratory setting" but that was "not the same as testing the drug on humans or animals".

"Following the study, the [US Food and Drug Administration] released a letter out of concern warning consumers not to self-medicate with ivermectin products intended for animals."

Meanwhile,  carried out by Bulgarian researchers found that while the results from the Australian study were replicable in humans, they would be reached "after massive overdose".

"It has to be emphasised that general public communication of drugs as potential COVID-19 therapeutics, based solely on in vitro data, is neither scientifically nor ethically appropriate," the Bulgarian researchers concluded.

"Ivermectin has been previously shown to exert antiviral activity in vitro against Dengue fever virus, influenza virus, West Nile Virus, Venezuelan equine encephalitis virus and heralded as a possible antiviral drug, but so far there has not been any clinical translation of these data."

In another (non-peer reviewed)  said to show ivermectin as an effective COVID-19 treatment, researchers who added small amounts of ivermectin to hydroxychloroquine and azithromycin found that it could lead to faster recovery times and shorter hospital stays.

The AstraZeneca jab and the price of fragmented decision-making

  The AstraZeneca jab and the price of fragmented decision-making Experts warn authorities’ divergent policies may damage trust and increase hesitancy in countries facing shortages.Sure enough, when a healthcare worker approached her with a shot of the jab developed by the Anglo-Swedish pharmaceutical giant and the University of Oxford, the 75-year-old stood firm to her conviction. With Hugony refusing to leave, a doctor finally relented after four hours and gave her a shot of the Moderna vaccine.

The researchers noted, however, that "a larger prospective study with longer follow up may be needed to validate these results".

In its statement supplied to Fact Check, the National COVID-19 Clinical Evidence Taskforce noted that neither hydroxychloroquine nor azithromycin were approved COVID-19 treatments.

"The study is also not randomised, meaning there is significant potential for bias, and it is less likely to provide reliable information on the effectiveness of the intervention. As such, it is unlikely to provide useful information on the effectiveness or otherwise of ivermectin."

From Washington, D.C.

Voting laws have been the focus of heated debate across the US as the Senate considers the bill "H.R.1", known as the For The People Act. Should it be passed, the legislation would lead to wide-ranging changes to voter registration, absentee and in-person voting, and campaign finance rules.

Fact checkers at PolitFact have  false and misleading claims about the bill, which passed the House of Representatives mostly along party lines (Democrats voted for the bill, Republicans were against).

PolitiFact found, for instance, that the bill did now allow for absentee ballots to be "mailed out to anyone without proof of the voter's identity".

"The bill would require states to send mail ballot applications to all registered voters before federal elections," the fact checkers noted, "but sending an application is not the same thing as sending an actual ballot, and these would go to registered voters only, whose identity and eligibility to vote are known."

Claims that the bill had provisions banning voters from needing to show ID at polling places was found to be partially false — in states where showing ID was a requirement, the bill would allow voters instead to present a sworn written statement attesting to their identity.

Meanwhile, a claim made by Republican congressman Ted Budd that H.R.1 would allow minors to vote was wrong. Rather, the bill would allow 16 year-olds to pre-register to vote when they turned 18.

Finally, a suggestion from former US vice-president Mike Pence that the bill would allow illegal immigrants to vote was false.

"The bill does not permit voting by non-citizens in US elections, whether they're in the country legally or not," PolitiFact said.

"Pence was referring to a provision that would require automatic voter registration for people using services at government agencies. But that section says government agencies would pass along a person's information for voter registration only if they are citizens.

"People would still be attesting that they are eligible to vote, with penalties for lying, and it would still be up to election officials to verify eligibility."

In other news: Tips for spotting misinformation online

Last Friday marked International Fact-Checking Day — falling perhaps aptly on April 2, following the onslaught of misinformation that comes with April Fools' Day.

In recognition of the day, Alexios Mantzarlis from the Google News Lab (and formerly of the International Fact-Checking Network, IFCN)  some handy tips and tricks for spotting online misinformation.

According to Mantzarlis, finding out more about the source of a piece of information can help with verification. He suggests searching for an alternative source by explicitly excluding the original web pages in order to get an unbiased opinion.

"The [search] query would look something like this: 'youtube -site:youtube.com'," he explains.

His next tip is to check whether images are being used in context by performing a reverse image search: "This will look for the picture to check if it has appeared online before, and in what context, so you can see if it has been altered from its original meaning."

Mantzarlis further suggests looking for news coverage to see how different news outlets have reported on a topic or event, or using Google's  to see what reputable fact checkers have had to say.

Edited by

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The AstraZeneca jab and the price of fragmented decision-making .
Experts warn authorities’ divergent policies may damage trust and increase hesitancy in countries facing shortages.Sure enough, when a healthcare worker approached her with a shot of the jab developed by the Anglo-Swedish pharmaceutical giant and the University of Oxford, the 75-year-old stood firm to her conviction. With Hugony refusing to leave, a doctor finally relented after four hours and gave her a shot of the Moderna vaccine.

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