The second quarter 2021 combined ratio was a very strong 87.9%, improving 7.3 points from the prior year period. Second quarter 2021 results include $68 million (5.4 points) of favorable prior year reserve development, compared to $85 million (7.6 points) in the comparable prior year period. Catastrophe losses, net of reinsurance and including reinstatement premiums, were $11 million in the second quarter of 2021. By comparison, catastrophe losses were $26 million in the prior year period.
AFG recorded $2 million in losses related to COVID-19 in the second quarter of 2021 – primarily related to the economic slowdown impacting its trade credit business – and recorded favorable reserve development of approximately $4 million related to accident year 2020 COVID-19 reserves based on loss experience. By comparison, second quarter 2020 underwriting results included $85 million in COVID-19 related losses. Given the uncertainties surrounding the ultimate number and scope of claims relating to the pandemic, approximately 66% of the $96 million in AFG’s cumulative COVID-19 related losses are held as incurred but not reported (IBNR) reserves at June 30, 2021.
Second quarter 2021 gross and net written premiums were up 26% and 22%, respectively, when compared to the second quarter of 2020. Strong year-over-year growth was reported within each of the Specialty P&C groups as a result of an improving economy, new business opportunities and a strong renewal rate environment. Excluding workers’ compensation, gross and net written premiums grew 30% and 26% respectively, year over year.
Average renewal pricing across our entire P&C Group was up approximately 9% for the quarter. Excluding our workers’ compensation business, renewal pricing was up approximately 12%. With the exception of workers’ compensation, we are continuing to achieve strong renewal rate increases in the vast majority of our businesses.
Further details about AFG’s Specialty P&C operations may be found in the accompanying schedules.
The Property and Transportation Group reported an underwriting profit of $62 million in the second quarter of 2021, compared to $33 million in the second quarter of 2020. Higher underwriting profit in our crop, property & inland marine and transportation businesses were the drivers of the year-over-year increase. The businesses in the Property and Transportation Group achieved a very strong 86.6% calendar year combined ratio overall in the second quarter, an improvement of 5.1 points from the comparable period in 2020. Catastrophe losses in this group, net of reinsurance and inclusive of reinstatement premiums, were $7 million in the second quarter of 2021, compared to $15 million in the comparable 2020 period.
Second quarter 2021 gross and net written premiums in this group were 39% and 32% higher, respectively, than the comparable prior year period, with growth reported in all the businesses in this group. The growth came primarily from our transportation businesses – primarily the result of new accounts, combined with strong renewals and increased exposures in our alternative risk transfer business – and our crop insurance business, primarily the result of higher commodity futures pricing and timing differences in the writing of premiums. Overall renewal rates in this group increased 7% in the second quarter of 2021, consistent with results in the first quarter of this year.
The Specialty Casualty Group reported an underwriting profit of $71 million in the second quarter of 2021, compared to $27 million in the second quarter of 2020, primarily the result of higher profitability in our excess and surplus lines, excess liability, targeted markets and executive liability businesses. Underwriting profitability in our workers’ compensation businesses overall continues to be excellent. The businesses in the Specialty Casualty Group achieved a very strong 87.9% calendar year combined ratio overall in the second quarter, an improvement of 7.0 points from the comparable period in 2020. Catastrophe losses for this group were approximately $2 million in the second quarter of 2021 and approximately $6 million in the comparable prior year period. Results in the second quarter of 2020 included $52 million COVID-19 related losses, primarily in our workers’ compensation and executive liability businesses.
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