Gar N. Chan, DDS, INC

Ask An Expert: What happens if you miss your second dose of the COVID-19 vaccine?

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on December 22nd, 2020 at 9:20 AM hosted by Stan Bunger. The following information was prepared by Jessica Yi. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

Ask An Expert

At least 70,000 Californians have already received their first doses of Pfizer’s COVID-19 vaccine, and Moderna has also begun shipping out its vaccine this week.

Both vaccines will require patients to return for a second shot within a few weeks of getting the first dose. Pfizer advises patients to get the second dose in 21 days, and Moderna after 28 days. Getting the second shot increases the vaccine’s effectiveness and may also prolong immunity.

In the case of the Pfizer vaccine, efficacy increased from around 50% to 95% after study participants got the second dose.

“Ideally you want to get that second shot in that timeframe because that’s what’s been studied,” explained Dr. Roshni Mathew, Stanford Pediatrician and Infectious Disease Physician on KCBS Radio’s “Ask An Expert” early Tuesday.

However, the logistical challenges of getting patients to return in exactly 21 or 28 days for another dose of the vaccine will be significant, especially with the current levels of demand.

But Dr. Mathew said even if you do not get the second shot within the exact window, “that’s fine, you should just move forward…the CDC says that if you do get delayed for some reason and you have to get the second shot way further down than that specific time limit, you should go ahead and get that second shot, no need to repeat.”

The current guidance is based on the methodology that was studied and has therefore been proven, but vaccine experts have said there is no reason to think the second dose won’t be effective if it is not received in a narrow window of time.

Some of the other vaccine candidates that are still undergoing trials may not require two doses, such as the Johnson & Johnson vaccine.

University Study: Molecular Iodine Rinse Completely Effective in 30 sec against SARS CoV-2

Excerpts and edited notes for this blog were referenced from “The International Journal of Experimental Dental Science” Volume 9 Issue 1 (January–June 2020). The original article authors are Herb Moskowitz and Michelle Mendenhall. Permission to use and distribute this information is via the link – ( No changes were made to the original abstract. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

University Study


Aim: The aim of the present study was to evaluate and compare the efficacy and cytotoxicity of four different mouthwashes containing 1.5% hydrogen peroxide, 0.2% povidone, 0.12% chlorhexidine and 100 ppm molecular iodine for their ability to inactivate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Materials and Methods: The SARS-CoV-2 virus stocks were grown in minimum essential medium (MEM) test media, supplemented with 2.0% fetal bovine serum (FBS) and 50 μg/mL gentamicin. Test solutions and virus were incubated at room temperature for three contact times of 15, 30, and 60 seconds. The solutions were then neutralized by a 1/10 dilution in test media containing 10% FBS. Neutralized samples were then incubated for 5 days at 37 ± 2°C at 5% CO2. The test plates were then scored for their cytopathic effect and the log-reduction value (LRV) of the test solution was compared to the negative control (water).

Results: The results showed that the LRV for a 100 ppm molecular iodine oral rinse was significantly greater, at each exposure time, compared with the other three oral rinses in the study with no associated cytotoxicity. The 100 ppm molecular iodine rinse exhibited an LRV of 2.6 at 15 seconds and complete inactivation of SARS-CoV-2 at both 30 seconds and also at 60 seconds with LRV greater than 3.6 for each of those contact times.

Conclusion: The spread of infection through aerosol and splatter has long been considered one of the main concerns in the dental community. A preprocedural rinse with 100 ppm molecular iodine will play a vital role in combating COVID-19 pandemic by preventing the spread of infection.

In our office for all restorative and hygiene procedures, we offer this preprocedural rinse with 100 ppm molecular iodine to all of our patients to prevent and combat the spread of the COVID-19 pandemic.

Keywords: COVID, Molecular iodine, Pandemic, Preprocedural.
International Journal of Experimental Dental Science (2020): 10.5005/jp-journals-10029-1209

Pfizer’s Vaccine Offers Strong Protection After First Dose, F.D.A. Report Says.

This article appeared in the New York Times By Noah Weiland and Carl Zimmer and was published Dec. 8, 2020 and updated Dec. 9, 2020, 7:04 p.m. ET. A version of this article appears in print on Dec. 9, 2020, Section A, Page 10 of the New York edition with the same headline. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.


The Food and Drug Administration’s first analysis of the clinical trial data also found that the coronavirus vaccine worked well regardless of a volunteer’s race, weight or age.

WASHINGTON — The coronavirus vaccine made by Pfizer and BioNTech provides strong protection against Covid-19 within about 10 days of the first dose, according to documents published on Tuesday by the Food and Drug Administration before a meeting of its vaccine advisory group.

The finding is one of several significant new results featured in the briefing materials, which include more than 100 pages of data analyses from the agency and from Pfizer. Last month, Pfizer and BioNTech announced that their two-dose vaccine had an efficacy rate of 95 percent after two doses administered three weeks apart. The new analyses show that the protection starts kicking in far earlier.

What’s more, the vaccine worked well regardless of a volunteer’s race, weight or age. While the trial did not find any serious adverse events caused by the vaccine, many participants did experience aches, fevers and other side effects.

“This is what an A+ report card looks like for a vaccine,” said Akiko Iwasaki, an immunologist at Yale University.

On Thursday, F.D.A.’s vaccine advisory panel will discuss these materials in advance of a vote on whether to recommend authorization of Pfizer and BioNTech’s vaccine.

Pfizer and BioNTech began a large-scale clinical trial in July, recruiting 44,000 people in the United States, Brazil and Argentina. Half of the volunteers got the vaccine, and half got the placebo.

New coronavirus cases quickly tapered off in the vaccinated group of volunteers about 10 days after the first dose, according to one graph in the briefing materials. In the placebo group, cases kept steadily increasing.

The vaccine’s swift impact could benefit not just the people who get it but the country’s strained hospitals, curbing the flow of new patients into intensive care units.

Despite the early protection afforded by the first dose, it’s unclear how long that protection would last on its own, underscoring the importance of the second dose. Previous studies have found that the second dose of the Pfizer-BioNTech vaccine gives the immune system a major, long-term boost, an effect seen in many other vaccines.

The efficacy of the vaccine after the first dose is about 52 percent, according to Dr. William C. Gruber, senior vice president of Pfizer Vaccine Clinical Research and Development. After the second dose, that rises to about 95 percent. “Two doses of vaccine provide maximum protection,” he said.

Many experts have expressed concern that the coronavirus vaccines might protect some people better than others. But the results in the briefing materials indicate no such problem. The vaccine has a high efficacy rate in both men and women, as well as similar rates in white, Black and Latino people. It also worked well in obese people, who carry a greater risk of getting sick with Covid-19.

Some vaccines for other diseases set off a weak immune response in older adults. But Pfizer and BioNTech found that people over 65 got about as much protection from the coronavirus vaccine as younger people did.

“I found myself trembling reading this,” said Dr. Gregory Poland, a vaccine researcher at the Mayo Clinic, referring to the robust response of the vaccines in obese and older people. “This is a grand slam by any measure.”

Even if the vaccine is authorized by the F.D.A., the trial will continue. In the briefing documents, the companies said that they would encourage people to stay in the trial as long as possible, not knowing whether they got the vaccine or the placebo, so that the researchers could continue to collect information about whether the vaccine was safe and effective.

The briefing materials also provide a deeper look at the safety of the vaccine. In any large clinical trial, some people who get vaccines experience health conditions that have nothing to do with the vaccine itself. Comparing their rates of symptoms with those of the placebo group as well as with background rates in a population can point to symptoms that may actually be caused by a vaccine.

The F.D.A. concluded that there were no “meaningful imbalances” in serious health complications, known as adverse events, between the two groups. The agency noted that four people in the vaccinated group experienced a form of facial paralysis called Bell’s palsy, with no cases in the placebo group. The difference between the two groups wasn’t meaningful, and the rate in the vaccinated group was not significantly higher than in the general population.

The new Pfizer analysis revealed that many volunteers who received the vaccine felt ill in the hours after the second dose, suggesting that many people might have to request a day off work or be prepared to rest until the symptoms subside. Among those between ages 16 and 55, more than half developed fatigue, and more than half also reported headaches. Just over one-third felt chills, and 37 percent felt muscle pain. About half of those over age 55 felt fatigued, one-third developed a headache and about one-quarter felt chills, while 29 percent experienced muscle pain.

“Taking a day off after the second dose is a good thing to anticipate,” Dr. Iwasaki said.

On Monday, Kristen Choi, a psychiatric nurse and health services researcher at the University of California, Los Angeles, published a first-person account of the symptoms she experienced as a participant in the Pfizer-BioNTech trial, which included chills, nausea, headache and fever.

“Clinicians will need to be prepared to discuss with patients why they should trust the vaccine and that its adverse effects could look a lot like Covid-19,” Dr. Choi wrote in the journal JAMA Internal Medicine. She advised doctors to tell patients that these unpleasant symptoms were “a sign that the vaccine is working, despite the unfortunate similarities with the disease’s symptoms.”

Ask An Expert: What are the side effects of the COVID-19 vaccines?

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on December 7th, 2020 at 9:20 AM hosted by Stan Bunger. The following information was prepared by Jessica Yi. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

Ask An Expert

Governor Newsom announced Monday that California will likely receive as much as two million doses of coronavirus vaccines by the end of December. Those first doses will all go to high-risk populations including healthcare workers and people in nursing homes and aggregate living situations. But many might choose to forgo the vaccine until more is known about possible side effects. “We don’t know long term, we don’t know effects in certain groups like immunocompromised people, our pregnant population,” said Dr. Desi Kotis, Associate Dean of UCSF’s School of Pharmacy and Chief Pharmacy Officer for UCSF Health. “Vaccines usually – most drugs really – are never tested on those populations. And with trials starting just this past summer, it simply is not possible at this point to know for sure how the vaccine can impact a person a year or several years down the line.

“So we don’t know long term. We do know short term,” Dr. Kotis explained. “High fever is one of the side effects, headache, fatigue, muscle aches, nausea; nothing acetaminophen or an aspirin or ibuprofen wouldn’t cure.”

While there is still information to be collected about the vaccines, the major vaccine candidates from Pfizer and Moderna have been tested on a wide variety of people of different ages, ethnic backgrounds, lifestyle and health.

“There’s quite a few folks represented in those cohorts and we will find out more long term,” she said. Pfizer plans to follow the participants in its vaccine trial for two years to study the drug’s impact.

“But really the side effects and the safety right now, what we have seen thus far – and this is again manufacture data from Pfizer – is that the benefits of receiving a vaccine really do outweigh the mild side effects.”

Ask An Expert: Is It Safe To Visit The Dentist?

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on November 25th, 2020 at 9:20 AM hosted by Stan Bunger. The following information was prepared by Jim Taylor. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

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It has been more than eight months since the coronavirus pandemic forced lockdowns, which means it is past time for most people to get their regular dental exam and cleaning. The pandemic has created fear about a slate of normal activities, particularly ones that require close contact indoors, like going to the dentist. But dentists are doing their part to reassure people that it is safe to come to the office.

“The transmission of COVID in the dental office is practically nonexistent,” said Dr. Richard Nagy, president of the California Dental Association on KCBS Radio’s “Ask An Expert” program Wednesday.

That is because dentists are well-versed in infection control policies.

“Ever since the mid-eighties when the HIV scare came, dental offices were the leaders in infection control policies for blood borne pathogens,” explained Dr. Nagy.

He said between state of the art PPE, face masks, face shields and disinfectants, the likelihood of transmission is low.

If you really feel concerned, talk to your dentist about their safety practices and give them the chance to assuage your worries. Dr. Nagy said while it might feel strange, you could even ask the dentist about their COVID-19 status.

“I think that’s a valid question for the dentist and I think most dentists would be very happy to answer that because again, the answer would be, ‘No I don’t have COVID as well as my staff or my office has not seen COVID patients.'”

With many more months to go before the majority of Americans have access to a coronavirus vaccine, Dr. Nagy said it is time to stop putting off seeing the dentist.

Ask An Expert: Stanford Medicine Releases Framework for Rebounding from COVID-19

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on November 13th, 2020 hosted by Stan Bunger. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

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Stanford Medicine released a new framework this week to advise parts of society on how to safely return to more normal operations during and after the coronavirus pandemic.

The developers called the effort Recover, Restore and Reopen, or R3.

The Stanford R3 framework was conceived to help communities and organizations deal with the pandemic and recover from it.

The team of experts at Stanford University created this initiative in order to address some of the multifaceted ways that COVID-19 affects different communities.

Dr. Mary Leonard, one of the creators of the R3 framework and chair of the department of pediatrics at Stanford, said that when considering how to control COVID-19, society needs to get more sophisticated with testing strategies.

The project had three main goals:
1. Learning how to best contain and control COVID-19;
2. How to adapt;
3. How to safeguard and support communities.

Dr. Leonard said that the next step for her team is “connecting with the community and with the government and with the stakeholders to have an even further impact.”

She told KCBS Radio on Friday’s “Ask An Expert” that the team is now committed to figuring out how they can use “artificial intelligence and big data and the other expertise Stanford has across the state and across the country, to get better modeling, better predictions, so that other people can be prepared.”

The Stanford team is especially focused on increasing access to resources, such as testing and vaccines, when they become available, which is challenging for more vulnerable communities.

Another issue many communities are facing is access to telehealth, a popular health service where patients can connect with their provider remotely. However, for people without access to Wi-Fi or a device, telehealth services are not an option.

Dr. Leonard noted that the most effective strategy for providing better health care to vulnerable communities is policy change. She thinks that while the country is far from having a mandatory vaccine in its future, experts and governmental policymakers need to “come together and to communicate in a very consistent manner that helps to build trust.”

One of the contributing factors to confusion and mistrust of officials during the pandemic has been the mixed messages from various jurisdictions about what is and isn’t safe.

Dr. Leonard said we need more consistent messaging.

“At the national level, it will be such a game changer for us if we don’t have such mixed messaging, coming not just from the White House, but from all the different governors around the country that really has wreaked havoc,” she told KCBS Radio. “When in one state, you can go into a bar and another state, they aren’t even doing elective procedures, I think that has contributed to the lack of trust.”

The Stanford team has a website for their R3 framework, which includes informational lectures and other COVID-19 resources.

Ask An Expert: Smaller Shared Spaces Pose COVID-19 Risk

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on November 11th, 2020 at 9:20 AM hosted by Stan Bunger. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

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A new study published in the journal Nature found that venues like stores, restaurants and gyms are hot spots for COVID-19 spread.

Dr. Shelly Miller, Professor of Mechanical Engineering at the University of Colorado, Boulder, said indoor ventilation plays a large role in coronavirus risk.

“It’s really clear from outbreak information, and from watching the pandemic, that there are lots of opportunities to spread the virus indoors, where you have your mask off and you’re socializing,” Miller said. “But if you layer on additional ventilation and reduced occupancy with social distancing and mask wearing and less time indoors. It all adds up to a much lower risk.”

Miller said that at gyms, she does not see a high risk of COVID-19 transmission in shared shower spaces, but she said locker rooms pose a higher threat for virus spread.

“The locker rooms are crowded and everyone’s talking and doing their thing, especially in sports facilities,” Miller said. “So I think being really careful in how you occupy and use a locker room is important.”

With grocery shopping, Miller said it depends on how close you are to another person or people. She said shoppers and employees who come within six feet of each other, like when checking out at the cash register, may have a higher chance of spreading the virus. However, virus transmission is not as likely when just walking past people in and around the supermarket aisles.

“That is what we call long-range transport,” Miller said. “The ventilation in the systems in those big box stores with high ceilings, I think it’s lower risk from that activity. Although the levels in the community are going up so quickly that I am starting to think I may not spend time in a grocery store and get my groceries delivered again.”

And as the Thanksgiving holiday approaches, Miller said that such celebrations should be socially distanced and outside if possible, especially if people from multiple households are present.

Ask An Expert: Communication Is Key to Pandemic Parenting

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on October 30th, 2020 at 9:20 AM hosted by Stan Bunger. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

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More than seven months after lockdowns first went into effect, many people are feeling the effects on their mental health.

“We’re almost in sort of a third season of, ‘how long is this going to go on?’ And people are just really hitting the wall,” said Katherine Reynolds Lewis, parenting and mental health expert and author of the award-winning book, “The Good News About Bad Behavior.”

“Many of us have a low level depression,” she said, which can come out through a short temper, irritability or a feeling of being emotionally on the edge.

Lewis says with all members of the family under increasing stress, open communication is key to keeping the family unit strong and supportive.

Open Communication Is Key To Depression

She advises parents and children alike to share how they are feeling with one another and talk through it in a way that provides grace and understanding.

And parents may be surprised at what their children can handle, whether it is helping out with chores or communicating their own needs.

“I am a huge fan and advocate of the family meeting, of working collaboratively with kids to put it all on the table and ask for their support and help,” she said. “Whenever we can frame something in a positive way where we’re engaging in calling on them, kids want to step up, they want to belong, they want to contribute in the family. All of us right now really need that sense of purpose that has been missing for so many people, and kids need that too.”

And with families spending so much more time at home, the lines between school, work and recreation can blur.

“Some of these days are just long drudges through the day, through the schedule,” she said, which is why families should set clear schedules, or at least intentionally set aside a few minutes to be together and do something to relieve stress and enjoy themselves. “Find pockets of joy.”

Even a short break with no screens can be enough of a reward to get you through harder parts of the day and rejuvenate your family bonds.

Ask An Expert: How To Assess the Risks of Different Activities

Excerpts and edited notes for this blog were referenced from an “Ask An Expert” KCBS radio station 740 FM segment on October 16th, 2020 at 9:21 AM hosted by Stan Bunger. The following information was prepared by Jessica Yi. This blog is presented for viewers to validate, accept and/or decline its content and findings on their own.

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As the holiday season approaches, many Americans are having to figure out whether or not it is safe for them to participate in their usual traditions.

“I think the challenge is we’ve kind of taken this binary approach to risk early on, and it’s just not the case,” said Dr. Saskia Popescu, Term Assistant Professor in the Biodefense Program in the School of Policy and Government at George Mason University. “What we are seeing is a spectrum. Some things are higher risk than others, but to me the most important thing is risk awareness.”

Dr. Popesku says instead of designating some activities as off-limits and others as safe, we should be consistently evaluating our environments and the precautions being taken.

The main factors to consider are whether you are indoors or outdoors (which can impact ventilation and your ability to distance yourself from others), the amount of people around you, whether or not those people are wearing their masks and yelling or shouting and finally, how long you plan to stay for.

Dr. Popesku says when you evaluate activities along those guidelines, it makes it clear why a typical bar environment is high risk, whereas sitting at a restaurant outdoors and away from others is lower risk.

Some of these factors have changed since the pandemic first started.

“We are learning new things every single day,” she said. “You have to lean in to the changes. The better we get at understanding transmission, the more things are going to change and evolve.”

For example, early on in the pandemic many physicians were advising people to wipe down their groceries and mail before bringing it inside the house. However, researchers now understand that while the virus can surface on surfaces, the risk of becoming infected this way is low.

The basic advice to protect yourself from transmission now involves social distancing, wearing a mask, avoiding indoor gatherings and keeping your hands clean.

And Dr. Popesku says it is important for people to remember that risk reduction is additive.

“For some reason we see all of these things as just a singular prevention strategy, but they all have to work together,” she said. That means that while socializing outdoors instead of indoors can lower your risk, it is even better if everyone is also distanced from one another and wearing a mask.

“It’s that swiss cheese approach, where one layer is imperfect but if we add them all together that brings us the best chance of success and helps reduce risk as much as we can.”